DIY Quantum Processor: Complete Hardware Build Guide
February 2, 2026
35 min read
Tushar Agrawal
Quantum ComputingNV CenterDiamond QuantumDIY QuantumQuantum HardwareRoom Temperature QuantumHardware BuildTechnology 2026
Step-by-step guide to building a room-temperature NV-center quantum processor. Complete bill of materials, optical setup, microwave system, and assembly instructions.
From Theory to Reality: Building Your Quantum Processor
In Part 1, we introduced room-temperature quantum computing. In Part 2, we explored the physics of NV centers. Now it's time to build the hardware.
This guide provides everything you need to construct a working NV-center quantum processor. We'll cover component selection, optical design, microwave systems, and step-by-step assembly.
Safety Warning: This build involves Class 3B lasers that can cause permanent eye damage and RF equipment that requires careful handling. Review all safety sections before proceeding.
---
Part 1: Complete System Architecture
High-Level Overview
Room-Temperature NV Quantum Processor Architecture
===================================================
┌──────────────────────────────────────────────────────────────┐
│ CONTROL COMPUTER │
│ (Your Laptop/PC) │
│ │
│ ┌────────────────────────────────────────────────────────┐ │
│ │ Software Layer │ │
│ │ • Python + NumPy + PySerial │ │
│ │ • Pulse sequence programming │ │
│ │ • Data acquisition and analysis │ │
│ │ • Optional: Qiskit integration │ │
│ └────────────────────────────────────────────────────────┘ │
└──────────────────────────────────────────────────────────────┘
│ │ │
│ USB │ USB │ USB
▼ ▼ ▼
┌───────────────┐ ┌─────────────────┐ ┌────────────────────┐
│ Arduino/FPGA │ │ Microwave │ │ DAQ / Counter │
│ Timing │ │ Signal Gen │ │ (Photon Count) │
│ Controller │ │ (2.87 GHz) │ │ │
└───────┬───────┘ └────────┬────────┘ └─────────┬──────────┘
│ │ │
│ TTL │ SMA │
▼ ▼ │
┌───────────────┐ ┌─────────────────┐ │
│ Laser │ │ RF Amplifier │ │
│ Driver │ │ (+30 dB) │ │
│ │ │ │ │
└───────┬───────┘ └────────┬────────┘ │
│ │ │
│ │ SMA │
▼ ▼ │
┌──────────────────────────────────────────────────────────────┐
│ OPTICAL TABLE │
│ │
│ ┌────────┐ ┌──────────┐ ┌────────────────────────┐ │
│ │ GREEN │───►│ Dichroic │───►│ Objective │ │
│ │ LASER │ │ Mirror │ │ Lens │ │
│ └────────┘ └────┬─────┘ └───────────┬────────────┘ │
│ │ │ │
│ │ Red ▼ │
│ │ light ╔═════════╗ │
│ ▼ ║ DIAMOND ║◄─── MW │
│ ┌──────────┐ ║ NV ║ Antenna │
│ │ Bandpass │ ╚═════════╝ │
│ │ Filter │ │
│ └────┬─────┘ │
│ │ │
│ ▼ │
│ ┌──────────┐ │
│ │ APD │─────────────────────────────────┼──►
│ │ Detector │ Photon counts │
│ └──────────┘ │
│ │
└──────────────────────────────────────────────────────────────┘
---
Part 2: Complete Bill of Materials
Optical Components
OPTICAL COMPONENTS - DETAILED
═════════════════════════════════════════════════════════════════
EXCITATION LASER
────────────────
Item: 532nm DPSS Laser Module
Power: 50-100 mW
Type: Continuous Wave (CW)
Beam quality: TEM00 preferred
Suppliers: Thorlabs, CNI Laser, LaserLands
Price range: $200 - $500
Recommended models:
• Thorlabs CPS532 ($350) - Good beam quality
• CNI MGL-III-532 ($200) - Budget option
• Coherent OBIS 532 ($1500) - Research grade
Notes:
• Avoid laser pointers (poor beam quality, unstable power)
• Must be CW, not pulsed
• TTL or analog modulation input helpful
DICHROIC MIRROR
───────────────
Item: Longpass Dichroic Mirror
Cutoff: 550-575 nm
Size: 25mm diameter recommended
Suppliers: Thorlabs, Edmund Optics, Semrock
Price range: $100 - $200
Recommended:
• Thorlabs DMLP550 ($180)
• Edmund 550nm DCLP (#69-899, $120)
• Semrock Di02-R561 ($250) - Best performance
Specifications needed:
• Reflects: 400-545 nm (>95%)
• Transmits: 565-800 nm (>93%)
• 45° angle of incidence
OBJECTIVE LENS
──────────────
Item: Microscope Objective
Magnification: 20x - 60x
NA: 0.4 - 0.85
Type: Plan achromat or better
Suppliers: Olympus, Nikon, Thorlabs, AmScope
Price range: $100 - $500
Recommended:
• Olympus MPLN20x ($200) - Good balance
• Thorlabs N40X-PF ($300) - Plan fluorite
• AmScope PA40X ($50) - Budget option
Notes:
• Higher NA = better light collection
• Long working distance helpful for MW antenna
• Infinity-corrected preferred
BANDPASS FILTER
───────────────
Item: Emission Filter
Passband: 650-750 nm (NV fluorescence)
Blocking: OD 6+ at 532 nm
Size: 25mm diameter
Suppliers: Thorlabs, Semrock, Chroma
Price range: $100 - $250
Recommended:
• Semrock FF01-697/75 ($200)
• Thorlabs FBH700-40 ($100)
• Chroma ET700/75m ($180)
PHOTODETECTOR
─────────────
Item: Avalanche Photodiode (APD) or Si Photodiode
Wavelength: Sensitive at 650-750 nm
Type: Single photon counting OR high sensitivity
Option A: APD Module (Research grade)
• Thorlabs APD410A ($600) - APD with preamp
• Excelitas SPCM-AQRH ($2500) - Single photon counting
Option B: Si Photodiode (Budget)
• Thorlabs PDA36A2 ($400) - Amplified photodiode
• Generic Si photodiode + TIA ($50-100) - DIY option
Option C: PMT (Alternative)
• Hamamatsu H10721 ($800)
For beginners: Start with Si photodiode, upgrade later
OPTICAL MOUNTS AND POSTS
────────────────────────
Items needed:
• Optical posts (4-6): 1/2" diameter, 3-6" tall
• Post holders (4-6): Match post diameter
• Mirror mount (1): 45° kinematic
• Lens mount (1): For objective
• Filter holder (1): Slip-in type
• XYZ stage (1): For sample positioning
Thorlabs kit recommendation:
• ESK-P03 Educational Starter Kit ($300)
• Or individual components (~$200-400)
OPTICAL BREADBOARD OR TABLE
───────────────────────────
Option A: Mini breadboard
• Thorlabs MB1218 (12"×18") - $150
• Edmund 56-936 (12"×12") - $100
Option B: Optical table (if available)
• Any 1/4-20 threaded table works
Option C: DIY
• Aluminum plate with drilled/tapped holes
TOTAL OPTICAL COMPONENTS: $900 - $2,500
Microwave Components
MICROWAVE COMPONENTS - DETAILED
═══════════════════════════════════════════════════════════════
SIGNAL GENERATOR
────────────────
Item: RF/Microwave Signal Generator
Frequency: 2.5 - 3.2 GHz (must cover 2.87 GHz)
Output power: +10 dBm minimum
Control: USB preferred
Recommended options:
Budget ($300-600):
• Windfreak SynthNV Pro ($500) - 34 MHz to 4.4 GHz
• Signal Hound VSG25A ($400) - 100 kHz to 2.5 GHz
• Analog Devices EVAL-ADF4351 ($150) + Arduino - DIY
Mid-range ($600-1500):
• Windfreak SynthHD Pro ($850) - Dual channel
• Siglent SSG3021X ($700) - 9 kHz to 2.1 GHz
• Note: Siglent only goes to 2.1 GHz, need 3+ GHz model
Research grade ($2000+):
• Rohde & Schwarz SMB100A
• Keysight N5181B
For this project: Windfreak SynthNV Pro recommended
RF AMPLIFIER
────────────
Item: Power Amplifier
Frequency: 1-4 GHz (must cover 2.87 GHz)
Gain: +20 to +35 dB
P1dB: +20 dBm or higher
Connector: SMA
Recommended:
• Mini-Circuits ZVE-3W-183+ ($450) - +35 dBm P1dB
• Mini-Circuits ZX60-4016E+ ($200) - +20 dBm P1dB
• RF Bay LPA-3 ($100) - Budget option
Notes:
• More power = faster gates (shorter π pulse)
• May need attenuator for fine control
• Heat sink required for high power amps
SMA CABLES AND CONNECTORS
─────────────────────────
Items:
• SMA cables, 1-3 ft ($15 each)
• SMA-SMA adapters ($5 each)
• SMA-BNC adapters (if needed)
Get extras - these fail!
MICROWAVE ANTENNA
─────────────────
Two main options:
Option A: Loop Antenna (Simple)
• 20-24 AWG copper wire
• ~2mm diameter loop
• Impedance: Not 50Ω (lossy but works)
• Position: Near sample surface
Option B: Stripline/CPW (Better)
• FR4 or Rogers PCB
• 50Ω characteristic impedance
• Needs PCB fabrication or careful design
• Better field uniformity
For beginners: Start with loop antenna
TOTAL MICROWAVE COMPONENTS: $650 - $1,500
Diamond Sample and Mounting
DIAMOND AND SAMPLE MOUNTING
═══════════════════════════════════════════════════════════════
NV DIAMOND SAMPLE
─────────────────
Type options:
Option A: HPHT Diamond with NV (Recommended for beginners)
• High NV concentration
• Lower cost
• Ensemble measurements
• Suppliers: Element Six, Applied Diamond, Delaware Diamond
• Price: $100-300
Option B: CVD Diamond with single NV
• Lower NV density
• Single NV addressable
• Higher quality
• Price: $300-1000
Option C: Nanodiamond with NV
• Very small particles
• In solution, needs substrate
• Price: $100-200
Specifications to request:
• NV concentration: 1-10 ppm (for ensemble)
• Or: Single NV centers (for single qubit)
• Orientation: (100) or (111) surface
• Polish: Both sides polished preferred
• Size: 2mm × 2mm × 0.5mm typical
Recommended suppliers:
• Element Six (elementix.com)
• Delaware Diamond Knives
• Applied Diamond Inc
• Adámas Nanotechnologies (nanodiamonds)
SAMPLE HOLDER
─────────────
Requirements:
• Non-magnetic (no iron/steel near sample)
• Allows MW antenna close to diamond
• Thermally stable
• Optically accessible from above
Options:
• Custom 3D printed holder ($10-50)
• Modified microscope slide + tape
• Aluminum or brass machined holder
• PCB with diamond bonded on
Design considerations:
• MW antenna integrated or separate
• XYZ positioning needed
• Consider thermal contact for stability
XYZ POSITIONING STAGE
─────────────────────
Requirements:
• ~10 μm resolution (manual OK)
• Non-magnetic materials
• Stable
Options:
• Thorlabs MT1 XYZ stage ($500)
• AmScope microscope stage ($100-200)
• Manual micrometer stages ($100-300)
• DIY with micrometer heads
For beginners: Start with manual stages
TOTAL DIAMOND + MOUNTING: $200 - $800
Control Electronics
CONTROL ELECTRONICS - DETAILED
══════════════════════════════════════════════════════════════
TIMING CONTROLLER
─────────────────
Purpose: Synchronize laser, MW, and detection
Option A: Arduino (Simplest)
• Arduino Uno/Mega (~$30)
• Timing resolution: ~1 μs
• Good for basic experiments
• Limited by USB latency
Option B: Teensy 4.0/4.1 (Better)
• 600 MHz ARM processor (~$30)
• Timing resolution: ~10 ns
• Excellent for pulse sequences
Option C: FPGA (Best)
• Digilent Basys 3 ($150)
• Digilent Arty A7 ($130)
• Timing resolution: <1 ns
• Most flexible, steeper learning curve
Recommended: Start with Teensy, upgrade to FPGA
DATA ACQUISITION / PHOTON COUNTER
─────────────────────────────────
Purpose: Count photons from detector
Option A: Arduino + Interrupt (Simplest)
• Use external interrupt pin
• Limited to ~100 kHz count rate
• Free (use same Arduino)
Option B: Dedicated Counter
• NI USB-6001 ($200) - 100 kHz counter
• Measurement Computing USB-CTR04 ($300)
Option C: FPGA Counter (Best)
• Integrated with timing controller
• MHz count rates possible
• DIY on same FPGA
Option D: Time-Correlated Single Photon Counting
• PicoQuant TimeHarp ($3000+)
• For advanced experiments only
LASER DRIVER / MODULATOR
────────────────────────
If laser has TTL input: Direct Arduino connection
If not: Need AOM or laser driver
Acousto-Optic Modulator (AOM):
• Gooch & Housego 3080-125 ($500+)
• Provides ns switching
• Research grade option
Mechanical shutter:
• Thorlabs SH1 ($300)
• ms switching (adequate for basic work)
Laser current modulation:
• Some lasers allow direct modulation
• Check specifications
POWER SUPPLIES
──────────────
Required:
• 5V for Arduino/Teensy
• 12V-24V for laser (check specs)
• ±15V or 24V for RF amplifier
• Detector power (check specs)
Options:
• Bench power supply ($50-200)
• Individual AC adapters
• Linear supplies for low noise
TOTAL CONTROL ELECTRONICS: $200 - $700
Complete Cost Summary
TOTAL BUILD COST SUMMARY
═══════════════════════════════════════════════════════════════
Budget Standard Research
Component Category Option Option Grade
──────────────────────────────────────────────────────────────
Optical Components $900 $1,500 $2,500
Microwave Components $650 $1,000 $1,500
Diamond + Mounting $200 $400 $800
Control Electronics $200 $400 $700
Cables, misc, shipping $150 $200 $300
──────────────────────────────────────────────────────────────
TOTAL $2,100 $3,500 $5,800
Notes:
• Budget: Functional but limited performance
• Standard: Good for learning and basic experiments
• Research: Publication-quality capability
What you get:
• Single NV qubit operations
• Rabi oscillations
• Ramsey/Hahn echo experiments
• Basic quantum gate demonstrations
• Quantum sensing experiments
---
Part 3: Detailed Optical Setup
Optical Path Design
OPTICAL PATH - TOP VIEW (DETAILED)
══════════════════════════════════════════════════════════════
All dimensions in mm. Not to scale.
┌─────────────────────────────────────────────────────┐
│ │
│ LASER │
│ ┌─────┐ │
│ │ 532 │ Beam diameter: ~1-2mm │
│ │ nm │ Divergence: <1 mrad │
│ └──┬──┘ │
│ │ │
│ ▼ Green beam │
│ ┌─────┐ │
│ │ ND │ Neutral density filter (optional) │
│ │Filt │ Adjust power: OD 0.3 - 2.0 │
│ └──┬──┘ │
│ │ │
│ ▼ │
│ ┌─────┐ │
│ │Beam │ Beam expander (optional) │
│ │ Exp │ Expands beam to fill objective │
│ └──┬──┘ back aperture │
│ │ │
│ ▼ │
│ ●────────────────────────────────────────● │
│ │ Dichroic │ │
│ │ Mirror │ │
│ │ │ │
│ Green reflected Red transmitted
│ at 45° straight through
│ │ │ │
│ ▼ ▼ │
│ ┌─────┐ ┌──────┐ │
│ │Obj. │ │ Band │ │
│ │Lens │ 40x, NA 0.65 │ Pass │ │
│ │ │ Working dist: ~0.5mm │Filter│ │
│ └──┬──┘ └──┬───┘ │
│ │ │ │
│ ▼ ▼ │
│ ╔═════╗ ┌─────┐ │
│ ║ NV ║ Diamond sample │ APD │ │
│ ║DIAM ║ │ │ │
│ ╚═════╝ └─────┘ │
│ │ │
│ ┌──┴──┐ │
│ │ MW │ Antenna (loop or stripline) │
│ │Ant. │ ~1-2mm from sample │
│ └─────┘ │
│ │
└─────────────────────────────────────────────────────┘
Detailed Optical Alignment Procedure
OPTICAL ALIGNMENT - STEP BY STEP
════════════════════════════════════════════════════════════════
SAFETY FIRST:
• Laser goggles ON at all times when laser is on
• Never look into beam or specular reflections
• Remove watches and jewelry (reflective)
• Work with low power first, increase only when aligned
STEP 1: MOUNT THE LASER
───────────────────────
1. Secure laser to optical post
2. Aim beam parallel to table surface
3. Check beam height: should be 3-4" above table
4. Beam should be horizontal (use iris at two distances)
Verification:
• Beam hits same spot on card at 10cm and 50cm
• Beam height constant along path
STEP 2: ADD NEUTRAL DENSITY FILTER (Optional)
─────────────────────────────────────────────
1. Place in beam path, perpendicular to beam
2. Start with OD 2.0 (1% transmission)
3. This reduces power for safe alignment
Tip: Use OD 1-2 for alignment, remove for experiments
STEP 3: MOUNT DICHROIC MIRROR
─────────────────────────────
1. Mount dichroic in kinematic mirror mount
2. Position at 45° to incoming beam
3. Height: same as beam (3-4")
4. Adjust tip/tilt to reflect beam downward at 90°
Verification:
• Reflected beam goes straight down
• Check with card at multiple heights
STEP 4: MOUNT OBJECTIVE LENS
────────────────────────────
1. Position objective directly below dichroic
2. Focal plane should be accessible from below
3. Secure firmly - vibration is the enemy
Distance from dichroic to objective: ~50-100mm
(Shorter is better for collection efficiency)
STEP 5: POSITION SAMPLE STAGE
─────────────────────────────
1. Mount diamond sample on holder
2. Place holder on XYZ stage
3. Position stage so sample is at objective focal plane
4. Working distance is typically 0.3-1mm
Initial focus:
• With room lights, look for reflection off diamond surface
• Adjust Z until surface is in focus
STEP 6: OPTIMIZE FOCUS
──────────────────────
1. Turn on laser at LOW power
2. Look at sample from side (NOT through objective)
3. You should see focused spot on diamond
4. Adjust Z for smallest spot size
Alternatively:
• Put white paper at sample position
• Focus for smallest, brightest spot
• Then replace with diamond
STEP 7: MOUNT DETECTION PATH
────────────────────────────
1. Transmitted red light goes through dichroic
2. Mount bandpass filter after dichroic
3. Mount detector (APD or photodiode) after filter
4. Align for maximum signal
Collection lens (optional):
• Place lens between filter and detector
• Focus red light onto detector active area
• Improves collection efficiency
STEP 8: VERIFY ALIGNMENT
────────────────────────
With diamond in place:
1. Turn on laser
2. You should see red fluorescence from sample
3. Detector should register signal
If no signal:
• Check focus (most common problem)
• Check filter orientation (some are directional)
• Check detector is working (use flashlight)
ALIGNMENT CHECKLIST:
────────────────────
□ Laser beam parallel to table
□ Dichroic at 45°, reflects beam straight down
□ Objective centered on reflected beam
□ Sample at focus of objective
□ Red fluorescence visible by eye (dim room)
□ Detector registers signal
□ Signal increases when laser power increases
□ All components secure and stable
---
Part 4: Microwave System Setup
Microwave Antenna Design
MICROWAVE ANTENNA OPTIONS
═════════════════════════════════════════════════════════════════
OPTION A: SIMPLE LOOP ANTENNA
─────────────────────────────
Materials:
• 22-24 AWG solid copper wire
• SMA connector (solder type)
• Small PCB or copper tape for ground plane
Construction:
┌── To RF amplifier
│ (SMA connector)
┌───────────────────────────────┴──┐
│ Ground plane (copper) │
│ ~10mm × 10mm │
│ │
│ ○────○ │
│ ╱ ╲ │
│ │ NV │ ← Loop ~2mm diameter │
│ ╲ ╱ made from 22 AWG │
│ ○────○ copper wire │
│ │ │ │
│ │ └── Signal (center of SMA) │
│ └───── Ground (to SMA shield) │
│ │
└───────────────────────────────────┘
Loop sits ~0.5-1mm above diamond surface
Pros: Simple, cheap, easy to make
Cons: Inefficient, non-uniform field
OPTION B: STRIPLINE / CPW ANTENNA
─────────────────────────────────
Design for 50Ω characteristic impedance on FR4:
┌─────────────────────────────────────────┐
│ Ground plane (top) │
├─────────────────────────────────────────┤
│ ┌───────────────────────────┐ │
│ │ FR4 dielectric │ │
│ │ thickness ~0.8mm │ │
│ └───────────────────────────┘ │
├──────────────────────────────────────────┤
│ GND │ 50Ω trace │ GND │
│ ═════│═════════════════│═════ │
│ │ width ~1.5mm │ │
│ │ (for FR4) │ │
│ │ │ │
│ │ [DIAMOND] │ ← Sample placed│
│ │ │ on trace │
│ │ │ │
└──────┴─────────────────┴────────────────┘
Get PCB fabricated (JLCPCB, OSH Park, etc.)
Pros: Better efficiency, uniform field
Cons: Requires PCB design/fabrication
OPTION C: OMEGA ANTENNA
───────────────────────
Omega (Ω) shaped loop:
╱─────╲
╱ ╲
│ │
│ NV │
│ sample │
│ │
╲ ╱
╲─┬─┬─╱
│ │
SIG GND
Better field uniformity than simple loop
Still easy to make with wire
Microwave System Assembly
MICROWAVE CHAIN ASSEMBLY
════════════════════════════════════════════════════════════════
SIGNAL PATH:
────────────
Signal Generator → RF Amplifier → Antenna
│ │ │
2.87 GHz +30 dB Near sample
+10 dBm ~+40 dBm
Connection order:
1. Signal generator output → SMA cable
2. SMA cable → RF amplifier input
3. RF amplifier output → SMA cable (short!)
4. SMA cable → Antenna feed
POWER LEVELS:
─────────────
Component Output Power Notes
──────────────────────────────────────────────────
Signal Generator +10 dBm 10 mW
After Amplifier +40 dBm 10 W (max!)
At Antenna ~+35 dBm ~3 W (losses)
WARNING: These power levels can cause:
• RF burns (don't touch antenna when on!)
• Interference with other equipment
• Damage to equipment if mismatched
RF AMPLIFIER SETUP:
───────────────────
1. Power supply connections:
• Check amplifier specifications
• Typically +12V to +28V DC
• Current: 1-3A depending on model
2. Heat management:
• Mount amplifier on heat sink
• Ensure airflow
• May need active cooling (fan)
3. Input/output:
• Check max input power rating
• Never exceed to avoid damage
• Use attenuator if needed
ATTENUATOR (Optional but recommended):
──────────────────────────────────────
Place attenuator between generator and amplifier
to have fine power control:
SigGen → 10dB Atten → Amplifier → Antenna
(switchable)
This lets you vary effective power by
changing attenuator instead of SigGen setting
SMA CABLE TIPS:
───────────────
• Use low-loss cable (LMR-400 or better)
• Keep cables short (<1m total if possible)
• Hand-tighten SMA, don't over-torque
• Check for damage before use
• Replace if center pin is damaged
VERIFICATION:
─────────────
1. Set signal generator to 2.87 GHz, -20 dBm (safe level)
2. Power on amplifier
3. Check amplifier output with power meter if available
4. Slowly increase power while monitoring
With antenna connected:
• You won't see much on NV without proper detection
• But you can verify no obvious problems (smoke, heat)
---
Part 5: Diamond Sample Preparation
Handling Your Diamond
DIAMOND SAMPLE HANDLING
════════════════════════════════════════════════════════════════
WHEN YOU RECEIVE YOUR SAMPLE:
─────────────────────────────
Typical packaging:
• Small plastic container or gel-pak
• May be in vacuum-sealed bag
• Usually 2mm × 2mm × 0.5mm or similar
First inspection:
• Hold up to light - should see through it
• Look for chips or cracks
• Note any obvious inclusions
Storage:
• Keep in original container
• Store in clean, dry location
• Avoid temperature extremes
CLEANING PROCEDURE:
───────────────────
For best results, diamond should be cleaned
before use. NV fluorescence can be affected
by surface contamination.
Basic cleaning (safe for beginners):
1. Rinse with isopropyl alcohol (IPA)
2. Blow dry with clean compressed air or nitrogen
3. Handle only with clean tweezers
Advanced cleaning (if basic doesn't work):
Acid clean (REQUIRES FUME HOOD AND TRAINING):
1. Boiling acid mixture (3:1 H2SO4:HNO3)
2. 30-60 minutes
3. Rinse thoroughly with DI water
4. IPA rinse and dry
Oxygen plasma clean:
• If you have access to plasma cleaner
• 5-10 minutes O2 plasma
• Removes organic contamination
WARNING: Acid cleaning is DANGEROUS
Only attempt if properly trained!
MOUNTING THE SAMPLE:
────────────────────
Option 1: Temporary mounting (easiest)
• Microscope slide
• Small piece of double-sided tape
• Place diamond on tape
• Tape holds diamond securely
Option 2: Vacuum grease
• Small dab on slide
• Press diamond onto grease
• Holds well, easy to remove
Option 3: Custom holder
• 3D printed or machined
• Small pocket for diamond
• May include MW antenna
SAMPLE ORIENTATION:
───────────────────
NV centers have orientation in crystal:
(100) surface diamond: (111) surface diamond:
───────────────────── ─────────────────────
NV axes at 54.7° to surface One NV axis perpendicular
For ensemble measurements:
• Both orientations work
• (111) may give stronger signal (more NVs aligned)
For single NV:
• (111) with aligned NV is ideal
• Otherwise need to account for angle
FINDING NV FLUORESCENCE:
────────────────────────
Once diamond is mounted:
1. Focus green laser onto diamond
2. Look for red fluorescence
3. May need to scan sample to find bright spots
What you should see:
• Visible red glow under laser illumination
• Brighter than typical background
• May see structure if non-uniform NV density
If no fluorescence:
• Check focus
• Clean sample
• Verify laser wavelength (532nm not 514nm etc)
• Sample may have low NV density - get another
---
Part 6: Control Electronics Setup
Arduino-Based Timing Controller
ARDUINO TIMING CONTROLLER
════════════════════════════════════════════════════════════════
COMPONENTS NEEDED:
──────────────────
• Arduino Mega 2560 (multiple digital outputs)
Or Arduino Uno (limited pins but works)
• BNC breakout shield or wires + BNC connectors
• USB cable
WIRING DIAGRAM:
───────────────
Arduino Mega
┌──────────────────────────────────────┐
│ │
│ Digital Pin 2 ───── Laser TTL │◄─ Laser on/off
│ Digital Pin 3 ───── MW Enable │◄─ Gate for MW
│ Digital Pin 4 ───── MW Trig │◄─ MW pulse trigger
│ Digital Pin 5 ───── Detection │◄─ Start counting
│ │
│ Digital Pin 18 ◄─── Photon In │◄─ From detector
│ (External Interrupt) │
│ │
│ GND ─────────────── Common GND │◄─ All grounds
│ │
└──────────────────────────────────────┘
BASIC TIMING CODE:
──────────────────
const int LASER_PIN = 2; const int MW_GATE_PIN = 3; const int DETECTION_PIN = 5; const int PHOTON_PIN = 18;
volatile long photon_count = 0;
void setup() { pinMode(LASER_PIN, OUTPUT); pinMode(MW_GATE_PIN, OUTPUT); pinMode(DETECTION_PIN, OUTPUT); pinMode(PHOTON_PIN, INPUT);
attachInterrupt(digitalPinToInterrupt(PHOTON_PIN), countPhoton, RISING);
Serial.begin(115200); }
void countPhoton() { photon_count++; }
// Initialize qubit to |0> state void initialize(int duration_us) { digitalWrite(LASER_PIN, HIGH); delayMicroseconds(duration_us); digitalWrite(LASER_PIN, LOW); }
// Apply microwave pulse void mw_pulse(int duration_ns) { // Note: delayMicroseconds minimum is 3us on Arduino // For ns precision, need Teensy or FPGA digitalWrite(MW_GATE_PIN, HIGH); delayMicroseconds(max(1, duration_ns/1000)); digitalWrite(MW_GATE_PIN, LOW); }
// Read out qubit state long readout(int duration_us) { photon_count = 0; digitalWrite(LASER_PIN, HIGH); digitalWrite(DETECTION_PIN, HIGH); delayMicroseconds(duration_us); digitalWrite(DETECTION_PIN, LOW); digitalWrite(LASER_PIN, LOW); return photon_count; }
void loop() { // Example: Rabi oscillation measurement // Vary MW pulse duration and measure result
for (int pulse_us = 0; pulse_us < 200; pulse_us += 5) { long counts = 0; int shots = 100;
for (int i = 0; i < shots; i++) { initialize(1000); // 1ms init mw_pulse(pulse_us * 1000); // MW pulse (in ns) counts += readout(300); // 300us readout }
Serial.print(pulse_us); Serial.print(","); Serial.println(counts); }
delay(1000); }
Teensy provides ~10ns timing resolution:
// Teensy 4.0 NV Control
// Much better timing resolution!
const int LASER_PIN = 2;
const int MW_GATE_PIN = 3;
const int PHOTON_PIN = 18;
volatile long photon_count = 0;
void countPhoton() {
photon_count++;
}
void setup() {
pinMode(LASER_PIN, OUTPUT);
pinMode(MW_GATE_PIN, OUTPUT);
pinMode(PHOTON_PIN, INPUT);
attachInterrupt(PHOTON_PIN, countPhoton, RISING);
Serial.begin(115200);
}
// Nanosecond delay using cycle counting
void delayNanoseconds(int ns) {
// Teensy 4.0 runs at 600 MHz = 1.67ns per cycle
int cycles = (ns * 600) / 1000;
for (volatile int i = 0; i < cycles; i++) {
__asm__ __volatile__("nop");
}
}
void mw_pulse_ns(int duration_ns) {
digitalWriteFast(MW_GATE_PIN, HIGH);
delayNanoseconds(duration_ns);
digitalWriteFast(MW_GATE_PIN, LOW);
}
// Pi pulse at 2.87 GHz with 10 MHz Rabi frequency
// Duration = pi / (2*pi*10MHz) = 50 ns
void pi_pulse() {
mw_pulse_ns(50);
}
void pi_over_2_pulse() {
mw_pulse_ns(25);
}
void loop() {
// Your experiment code here
}
Photon Counting Setup
PHOTON COUNTING APPROACHES
════════════════════════════════════════════════════════════════
OPTION A: ANALOG INTEGRATION (Simplest)
───────────────────────────────────────
If using amplified photodiode:
• Detector outputs voltage proportional to light
• Use Arduino analog input
• Integrate during detection window
for (int i = 0; i < samples; i++) { total += analogRead(A0); delayMicroseconds(10); }
return total; }
OPTION B: DIGITAL COUNTING (Better)
───────────────────────────────────
If detector has TTL output:
• Each photon → digital pulse
• Count pulses during window
Max rates:
• Arduino: ~100 kHz
• Teensy 4.0: ~1 MHz
• FPGA: ~100 MHz
OPTION C: TIME-TAGGED (Advanced)
────────────────────────────────
Record arrival time of each photon:
• Need TCSPC hardware
• Or fast FPGA implementation
• Enables advanced analysis
For beginners: Start with analog or basic digital
SIGNAL PROCESSING:
──────────────────
After data collection:
1. Background subtraction:
• Measure counts with no NV (laser blocked)
• Subtract from signal
2. Normalization:
• Divide by reference measurement
• Or by known bright (|0⟩) signal
3. Averaging:
• Repeat measurement many times
• Average to reduce noise
---
Part 7: Assembly Procedure
Step-by-Step Assembly
COMPLETE ASSEMBLY PROCEDURE
════════════════════════════════════════════════════════════════
DAY 1: OPTICAL SYSTEM
─────────────────────
Step 1: Set up breadboard/table (30 min)
□ Level the surface
□ Clean thoroughly
□ Plan component layout
Step 2: Mount and align laser (1 hour)
□ Secure laser to post
□ Check beam height and direction
□ Add ND filter for alignment
Step 3: Mount dichroic mirror (30 min)
□ Install in kinematic mount
□ Adjust for 90° reflection
□ Verify with alignment card
Step 4: Mount objective lens (30 min)
□ Position below dichroic
□ Secure firmly
□ Note focal plane location
Step 5: Set up detection path (1 hour)
□ Mount bandpass filter
□ Mount detector
□ Add focusing lens if using
□ Verify detector responds to light
DAY 2: SAMPLE AND DETECTION
───────────────────────────
Step 6: Prepare diamond sample (30 min)
□ Clean sample
□ Mount on holder
□ Position on stage
Step 7: Find NV fluorescence (1-2 hours)
□ Focus laser onto diamond
□ Scan for bright spots
□ Optimize position for max signal
□ Verify red fluorescence
Step 8: Verify detection (30 min)
□ Check detector registers signal
□ Block laser → signal drops
□ Increase laser power → signal increases
DAY 3: MICROWAVE SYSTEM
───────────────────────
Step 9: Assemble MW chain (1 hour)
□ Connect signal generator
□ Connect amplifier with power
□ Connect to antenna
□ Verify amplifier heats (it should)
Step 10: Position antenna (30 min)
□ Place antenna near sample
□ ~0.5-1mm from diamond surface
□ Secure in place
Step 11: Basic MW test (30 min)
□ Set frequency to 2.87 GHz
□ Set low power initially
□ Verify no damage to other components
DAY 4: CONTROL ELECTRONICS
──────────────────────────
Step 12: Set up Arduino/Teensy (1 hour)
□ Upload timing code
□ Connect to laser control
□ Connect to detector input
□ Connect to MW gate
Step 13: Test each subsystem (1 hour)
□ Laser on/off via Arduino
□ Photon counting works
□ MW gate triggers correctly
Step 14: Integration test (1-2 hours)
□ Run basic pulse sequence
□ Initialize → MW pulse → Readout
□ Verify signals on oscilloscope if available
DAY 5: CALIBRATION
──────────────────
Step 15: Find NV resonance (1-2 hours)
□ Sweep MW frequency 2.85-2.89 GHz
□ Monitor fluorescence
□ Find dip at resonance
Step 16: Calibrate π pulse (1-2 hours)
□ Vary MW pulse duration
□ Observe Rabi oscillations
□ Find π and π/2 pulse times
Step 17: Verify coherence (1 hour)
□ Run Ramsey sequence
□ Observe oscillations and decay
□ Extract T2*
TOTAL TIME: ~15-25 hours over 5 days
---
Part 8: Safety Protocols
Laser Safety
LASER SAFETY - CRITICAL
════════════════════════════════════════════════════════════════
YOUR LASER CLASS:
─────────────────
Class 3B (50-500 mW at 532 nm)
Hazards:
• Direct eye exposure → PERMANENT BLINDNESS
• Specular reflections → PERMANENT BLINDNESS
• Diffuse reflections → Usually safe but not at close range
• Skin exposure → Burns possible at high power
REQUIRED SAFETY EQUIPMENT:
──────────────────────────
□ Laser safety goggles
Specification: OD 4+ at 532 nm
Example: Thorlabs LG10 ($50)
MUST be worn whenever laser can be on!
□ Warning signs
Post "LASER IN USE" signs at entrances
Use when operating
□ Beam blocks/dumps
Terminate beams that aren't used
Prevents stray reflections
SAFE OPERATING PROCEDURES:
──────────────────────────
1. Before turning on laser:
□ Announce "Laser on" to anyone in room
□ Everyone puts on goggles
□ Check beam path is clear
□ Remove reflective objects (jewelry, watches)
2. During operation:
□ Never look into beam or reflections
□ Keep beam at or below waist height
□ Use minimum necessary power
□ Don't leave laser on unattended
3. Alignment:
□ Use IR viewer cards or phosphor screens
□ Start at lowest power
□ Increase only when aligned
4. When done:
□ Turn off laser at source
□ Wait for confirmation it's off
□ Goggles can be removed after verification
EMERGENCY PROCEDURES:
─────────────────────
Eye exposure:
1. DO NOT rub eyes
2. Seek immediate medical attention
3. Tell doctor: 532nm laser exposure
4. Bring laser specs to hospital
Skin burn:
1. Treat as normal burn
2. Cool with water
3. Seek medical attention if severe
COMMON MISTAKES TO AVOID:
─────────────────────────
✗ "I'll just do this one thing quickly"
→ Always wear goggles
✗ "The laser isn't that powerful"
→ 50mW can cause permanent damage in ms
✗ "I'll use sunglasses"
→ Sunglasses are NOT adequate protection
✗ "The beam is going into the sample"
→ Reflections can come from anywhere
RF Safety
RF/MICROWAVE SAFETY
════════════════════════════════════════════════════════════════
POWER LEVELS IN YOUR SYSTEM:
────────────────────────────
Amplifier output: Up to +40 dBm (10W)
At antenna: ~+35 dBm (3W)
For comparison:
• Cell phone: +30 dBm (1W)
• Microwave oven: 1000W (but shielded)
HAZARDS:
────────
1. RF Burns
• Direct contact with antenna while active
• Can cause localized burns
• Not immediately felt (unlike thermal burns)
2. Interference
• May affect pacemakers
• Can interfere with other equipment
• WiFi/Bluetooth may be disrupted
3. Equipment damage
• Open/short connections can damage amp
• Reflected power can damage amp
SAFE PRACTICES:
───────────────
□ Never touch antenna when MW is on
□ Keep at least 30cm from antenna when on
□ Start at low power, increase gradually
□ Use proper 50Ω terminations
□ Ensure good SMA connections
□ Don't operate with antenna disconnected
□ Turn off MW when making adjustments
PEOPLE WITH PACEMAKERS:
• Consult doctor before working near RF
• May need to maintain larger distance
• Consider adding RF shielding
General Lab Safety
GENERAL LABORATORY SAFETY
════════════════════════════════════════════════════════════════
ELECTRICAL:
───────────
□ Check all cables before use
□ No exposed wires
□ Keep water away from electronics
□ Use grounded equipment
□ Know location of power shutoff
CHEMICAL (if cleaning diamond):
───────────────────────────────
□ Work in fume hood
□ Wear appropriate PPE (gloves, goggles, lab coat)
□ Know MSDS for all chemicals
□ Have neutralization materials ready
□ Never work alone
ERGONOMICS:
───────────
□ Adjust table/chair heights
□ Take breaks
□ Ensure adequate lighting
□ Don't strain to reach components
EMERGENCY CONTACTS:
───────────────────
Post near workspace:
□ Emergency services: [Your country's number]
□ Poison control: [Your country's number]
□ Campus security: [If applicable]
□ Lab supervisor: [If applicable]
---
Part 9: Testing and Calibration
Initial System Tests
SYSTEM TESTING PROCEDURE
════════════════════════════════════════════════════════════════
TEST 1: LASER FUNCTION
──────────────────────
Setup:
• Connect laser power
• Have safety goggles on
• Point at phosphor card
Test procedure:
1. Turn on laser
2. Verify green beam visible on card
3. Check beam profile (should be round)
4. Test TTL control if available
Expected result:
✓ Bright green spot on card
✓ Power stable over 1 minute
✓ TTL on/off works (if applicable)
Troubleshooting:
• No beam → Check power, connections
• Dim beam → May be warming up
• Flickering → Power supply issue
TEST 2: OPTICAL PATH
────────────────────
Setup:
• Full optical path assembled
• Diamond in place (or paper for now)
Test procedure:
1. Focus laser onto target
2. Place white paper at detection path
3. Look for red light (NV fluorescence or reflections)
Expected result:
✓ Red light reaches detector position
✓ No stray green light leaking through
If using paper:
• Will see green reflection
• Bandpass filter should block it
TEST 3: DETECTION
─────────────────
Setup:
• Detector connected and powered
• Output connected to oscilloscope or Arduino
Test procedure:
1. Block detector → baseline signal
2. Illuminate with flashlight → signal increase
3. Block again → returns to baseline
Expected result:
✓ Clear response to light
✓ Fast response time
✓ Low noise baseline
Troubleshooting:
• No response → Check connections, power
• Saturated → Too much light, add attenuation
• Very noisy → Check grounding
TEST 4: NV FLUORESCENCE
───────────────────────
Setup:
• Diamond sample in place
• Full detection path
Test procedure:
1. Focus laser on diamond
2. Look at sample from side (with goggles!)
3. Should see red glow
4. Monitor detector output
Expected result:
✓ Visible red fluorescence
✓ Detector shows signal
✓ Signal varies with laser power
Troubleshooting:
• No fluorescence → Check focus, clean sample
• Weak fluorescence → Low NV density in sample
• Signal but no visible glow → May be dim, use dark room
TEST 5: MICROWAVE SYSTEM
────────────────────────
Setup:
• MW chain connected
• Frequency set to 2.87 GHz
• Power at minimum
Test procedure:
1. Power on amplifier
2. Set signal generator to 2.87 GHz, -20 dBm
3. Gradually increase power
4. Amplifier should get warm
Expected result:
✓ No smoke or burning smell
✓ Amplifier warm but not hot
✓ Output power measurable (if you have meter)
Troubleshooting:
• No output → Check connections
• Very hot → May be oscillating, check terminations
• Power meter shows wrong frequency → Verify sig gen setting
Finding NV Resonance
FINDING THE NV RESONANCE (ODMR)
════════════════════════════════════════════════════════════════
ODMR = Optically Detected Magnetic Resonance
When microwave frequency matches NV transition (2.87 GHz),
fluorescence DECREASES. This is how we find resonance.
PROCEDURE:
──────────
1. Prepare measurement:
□ Laser on, focused on NV sample
□ Detector collecting fluorescence
□ MW power moderate (+20 to +30 dBm at antenna)
2. Sweep frequency:
□ Sweep from 2.75 GHz to 2.95 GHz
□ Step size: 5 MHz
□ Dwell time: 100-500 ms per point
3. Record fluorescence at each frequency:
□ Count photons or measure analog signal
□ Plot fluorescence vs frequency
EXPECTED RESULT:
────────────────
Fluorescence
▲
│
100%│────────────────────────────────────────
│ ╲ ╱
95%│ ╲ ╱
│ ╲ ╱
90%│ ╲ ╱
│ ╲ ╱
85%│ ╲ ╱
│ ╲ ╱
80%│ ╲╱ ← Resonance dip
│ │
└───────────────────┼───────────────────► Frequency
2.87 GHz
Dip depth: 10-30% typically
Width: 5-50 MHz depending on conditions
WITH MAGNETIC FIELD:
────────────────────
If external B-field is present:
Fluorescence
▲
│
100%│──────────────────────────────────────
│ ╲ ╱ ╲ ╱
│ ╲ ╱ ╲ ╱
85%│ ╲╱ ╲╱
│ │ │
│ ms=-1 ms=+1
└────────┼───────────────────┼────────► Freq
2.87-γB 2.87+γB
Two dips separated by 2γB (5.6 MHz per Gauss)
ODMR SCAN CODE (Python):
────────────────────────
Connect to signal generator
sig_gen = serial.Serial('/dev/ttyUSB0', 115200)Connect to Arduino for photon counting
arduino = serial.Serial('/dev/ttyACM0', 115200)def set_frequency(freq_hz): """Set signal generator frequency""" cmd = f"FREQ {freq_hz}\n" sig_gen.write(cmd.encode())
def count_photons(duration_ms=100): """Count photons for given duration""" arduino.write(f"COUNT {duration_ms}\n".encode()) result = arduino.readline().decode().strip() return int(result)
Sweep parameters
freq_start = 2.75e9 # 2.75 GHz freq_stop = 2.95e9 # 2.95 GHz freq_step = 5e6 # 5 MHz num_points = int((freq_stop - freq_start) / freq_step)Perform sweep
frequencies = [] fluorescence = []for i in range(num_points): freq = freq_start + i * freq_step set_frequency(freq) time.sleep(0.05) # Wait for frequency to settle
counts = count_photons(100)
frequencies.append(freq / 1e9) # Convert to GHz fluorescence.append(counts)
print(f"Freq: {freq/1e9:.3f} GHz, Counts: {counts}")
Plot result
plt.figure(figsize=(10, 6)) plt.plot(frequencies, fluorescence, 'b.-') plt.xlabel('Frequency (GHz)') plt.ylabel('Fluorescence (counts)') plt.title('ODMR Spectrum of NV Center') plt.grid(True) plt.savefig('odmr_spectrum.png') plt.show()
### Calibrating Rabi Oscillations
Once you find the resonance frequency, calibrate the pulse duration for π and π/2 rotations.
PROCEDURE: ──────────
1. Set MW to resonance frequency (from ODMR) 2. Fix MW power 3. Vary MW pulse duration 4. Measure fluorescence after each pulse
PULSE SEQUENCE: ───────────────
Init MW Pulse Readout │ │ │ ────────┼───────────────┼────────────────┼────────► │ │ │ Laser: ████████████████░░░░░░░░░░░░░░░░░████████ │←── 1-2 μs ──→│ │← 300ns →│ │ │ │ MW: ░░░░░░░░░░░░░░░░████░░░░░░░░░░░░░░░░░░░░░ │← τ →│ varied
Detect: ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░████████ count here
EXPECTED RESULT: ────────────────
Fluorescence ▲ │ |0⟩│● │ ╲ │ ╲ │ ╲ │ ╲ │ ● │ ╲ |1⟩│ ●─────● │ ╲ ● = π pulse │ ╲ │ ● │ └──────────────────────────────────────────► τ 0 τ_π/2 τ_π 3τ_π/2 2τ_π
Oscillation continues with decreasing amplitude due to decoherence (T2).
From this plot: • τ_π = pulse duration for full inversion • τ_π/2 = τ_π / 2 = Hadamard-like operation • Rabi frequency Ω = π / τ_π
TYPICAL VALUES: ───────────────
For +30 dBm at antenna: • τ_π ≈ 50-200 ns • Ω ≈ 5-20 MHz
Higher power → shorter τ_π
RABI CALIBRATION CODE: ──────────────────────
def rabi_oscillation(tau_list_ns, num_averages=1000):
"""Measure Rabi oscillation"""
results = []
for tau in tau_list_ns:
counts = 0
for _ in range(num_averages):
# Initialize
laser_on(1000) # 1000 ns = 1 μs
laser_off()
# MW pulse of duration tau
mw_on()
delay_ns(tau)
mw_off()
# Readout
counts += read_fluorescence(300) # 300 ns
results.append(counts / num_averages)
print(f"tau = {tau} ns, counts = {counts/num_averages:.1f}")
return results
# Sweep from 0 to 500 ns in 10 ns steps
tau_values = range(0, 500, 10)
rabi_data = rabi_oscillation(tau_values)
# Find pi pulse time
import scipy.optimize as opt
def rabi_fit(t, A, omega, phi, offset, decay):
return A * np.cos(omega * t + phi) * np.exp(-t/decay) + offset
# Fit the data
popt, pcov = opt.curve_fit(rabi_fit, tau_values, rabi_data)
omega_fit = popt[1]
tau_pi = np.pi / omega_fit
print(f"Pi pulse duration: {tau_pi:.1f} ns")
print(f"Rabi frequency: {omega_fit/(2*np.pi)*1e3:.1f} MHz")
---
Part 10: Troubleshooting Guide
COMMON PROBLEMS AND SOLUTIONS
════════════════════════════════════════════════════════════════
PROBLEM: No fluorescence from sample
─────────────────────────────────────
Symptoms:
• Laser on but no red glow
• Detector shows no signal
Causes and solutions:
1. Focus issue
→ Adjust Z position slowly while watching signal
2. Beam blocked
→ Check entire optical path
3. Sample has no NV centers
→ Try different position on sample
→ Get new sample with confirmed NV content
4. Filter blocking all light
→ Check filter orientation
→ Verify it passes 650-750 nm
5. Detector not working
→ Test with flashlight
→ Check power to detector
PROBLEM: No ODMR dip visible
────────────────────────────
Symptoms:
• Fluorescence present
• Sweeping frequency shows flat line
Causes and solutions:
1. MW not reaching sample
→ Check antenna position (<1mm from sample)
→ Check all MW connections
2. MW power too low
→ Increase amplifier power
3. Wrong frequency range
→ Center sweep at 2.87 GHz
→ Try wider sweep (2.5-3.2 GHz)
4. Strong magnetic field
→ Check for magnets nearby
→ Dips may be shifted far from 2.87 GHz
5. Modulation speed too fast
→ Increase dwell time per frequency
PROBLEM: Very weak ODMR contrast
────────────────────────────────
Symptoms:
• Dip visible but small (<5%)
Causes and solutions:
1. Low NV concentration
→ Normal for some samples
→ Need longer averaging
2. MW power insufficient
→ Increase power (if safe)
3. Many NV orientations (ensemble)
→ Only 1/4 of NVs at optimal angle
→ Normal for (100) samples
4. Background fluorescence
→ Clean sample
→ Check for dust in optical path
PROBLEM: Rabi oscillations not visible
──────────────────────────────────────
Symptoms:
• ODMR works but time-domain shows no oscillation
Causes and solutions:
1. Timing resolution too coarse
→ Arduino limited to ~1 μs
→ Upgrade to Teensy or FPGA
2. MW power too low
→ Rabi too slow, decays before oscillation
→ Increase power
3. Pulse times not in right range
→ Calculate expected τ_π from power
→ Start with 50-200 ns range
4. Phase noise in MW source
→ Use better signal generator
→ Check amplifier stability
PROBLEM: Signal very noisy
──────────────────────────
Symptoms:
• Large shot-to-shot variation
• Hard to see trends
Causes and solutions:
1. Not enough averaging
→ Increase number of shots
→ 1000-10000 shots typical
2. Vibrations
→ Isolate optical table
→ Check for HVAC, foot traffic
3. Laser power fluctuations
→ Use laser with power stabilization
→ Add feedback control
4. Electronic interference
→ Check grounding
→ Shield cables
→ Move away from other electronics
PROBLEM: System works sometimes but not others
─────────────────────────────────────────────
Symptoms:
• Intermittent failures
• Hard to reproduce
Causes and solutions:
1. Loose connections
→ Check all cables
→ Re-tighten SMA connectors
2. Temperature drift
→ Let system warm up
→ Temperature stabilize room
3. Alignment drift
→ Secure all optical mounts
→ Reduce vibrations
4. Software/timing bugs
→ Check code carefully
→ Add delays between commands
---
Conclusion and Next Steps
You now have a complete guide to building a room-temperature NV-center quantum processor. The total cost is $2,000-$5,000, compared to millions for a superconducting system.
What you've built:
- Optical system for NV initialization and readout
- Microwave system for qubit manipulation
- Control electronics for pulse sequences
- Software interface for experiments
- Complete software architecture
- Implementing quantum gates
- Running your first quantum algorithm
- Integration with Qiskit and other frameworks
Related Articles
- Part 1: Room-Temperature Quantum Computing Introduction
- Part 2: NV-Center Diamond Physics
- Part 4: Quantum Processor Software & First Algorithm
- Quantum Computing Explained: Complete Beginner's Guide 2026
Component Suppliers Quick Reference
| Category | Supplier | Website | |----------|----------|---------| | Optics | Thorlabs | thorlabs.com | | Optics | Edmund Optics | edmundoptics.com | | Filters | Semrock | semrock.com | | RF/MW | Mini-Circuits | minicircuits.com | | Signal Gen | Windfreak | windfreaktech.com | | Diamond | Element Six | e6.com | | Electronics | Digikey | digikey.com | | PCB Fab | JLCPCB | jlcpcb.com |
---
Part 3 of 4 in the Room-Temperature Quantum Computing series. Last updated: February 2, 2026.