Symposia on VLSI Technology and Circuits
Room-Temperature Quantum Sensing in CMOS: On-Chip Detection of Electronic Spin States in
Diamond Color Centers for Magnetometry
Mohamed I. Ibrahim*, Christopher Foy*, Donggyu Kim*, Dirk R. Englund, and Ruonan Han
*Equal Contribution
Massachusetts Institute of Technology
Symposia on VLSI Technology and Circuits Slide 1
• Introduction• CMOS-Based Quantum Magnetometer
– System Architecture – Microwave Signal Generation– Optical Excitation Filtering – Optical Fluorescence Readout
• Experimental Data– Measurement Results Using Layer of Nano-Diamonds– Measurement Results Using Bulk Diamond
• Conclusion
Outline
Symposia on VLSI Technology and Circuits
Nitrogen Vacancy (NV) in Diamond Magnetometer
•
Slide 2
Nitrogen vacancy center in diamond
Optically detected magnetic resonance (ODMR)
Symposia on VLSI Technology and Circuits
Nitrogen Vacancy (NV) in Diamond Magnetometer
• Sensitivity
–Where N is number of NVs
Slide 3
Clevenson, et al. Nature Physics 2015
Ensemble of NVsClevenson, et al. Nature Physics 2015
𝟎. 𝟐𝟗 𝐧𝐓/ 𝑯𝒛
Symposia on VLSI Technology and Circuits
Nitrogen Vacancy (NV) in Diamond Magnetometer
• Nano-tesla sensitivity• Nanometer spatial resolution• Vector field measurements• Ambient conditions (room temperature)
Slide 4
Bacteria magnetic imagingLe Sage, et al. Nature 2013
Magnetic structure imagingBalasubramanian, et al. Nature (2008)
Symposia on VLSI Technology and Circuits Slide 5
NV Magnetometer System Components
Signal generator Photodetector
Optical filtersMicrowave antenna
Green Laser
Le Sage, et al. Nature 2013
CMOS integrated NV magnetometer (TSMC 65nm LP process)
Symposia on VLSI Technology and Circuits Slide 6
• Introduction• CMOS Based Quantum Magnetometer
– System Architecture – Microwave Signal Generation– Optical Excitation Filtering – Optical Fluorescence Readout
• Experimental Results – Measurement Results Using Layer of Nano-Diamonds– Measurement Results Using Bulk Diamond
• Conclusion
Outline
Symposia on VLSI Technology and Circuits
CMOS Based Quantum Magnetometer
Slide 7
Symposia on VLSI Technology and Circuits
• 2.87 GHz microwave signal generation– 2.6 GHz – 3.1 GHz for
optically detected magnetic resonance (ODMR) measurements
• 10 Gauss field strength at 2.87 GHz with 95% homogeneity– To increase the contrast – To drive the NVs with equal
strength for spin control pulsed sequences (Echo, Ramsey,..)
Slide 8
Microwave Signal Generation
Symposia on VLSI Technology and Circuits Slide 9
Microwave Signal Generation
𝑩𝒛 = 𝑩𝟎
𝟏
𝝅 𝑸 𝑬 𝒌
𝟏 − 𝜶𝟐 − 𝜷𝟐
𝑸 − 𝟒𝜶+ 𝑲 𝒌
𝛼 = , 𝛽 = , 𝑘 =
, 𝑟 = 𝑥 + 𝑦 and 𝑄 = 1 + 𝑎 + 𝛽
https://tiggerntatie.github.io/emagnet/offaxis/iloopoffaxis.htm
Microwave Coil
160 mA is required to get 10 Gauss for
diameter coil
Symposia on VLSI Technology and Circuits
Microwave Signal Generation
Slide 10
Microwave Coil
Symposia on VLSI Technology and Circuits
Microwave Signal Generation
Slide 11
Microwave Coil
EM simulated performance
Symposia on VLSI Technology and Circuits
Microwave Signal Generation
• 10 Gauss with 95% uniformity– 6 mA DC current in the driver– 25x field strength more than simple
non-resonant loop
• 2.6 GHz-3.1 GHz Microwave frequency sweep
Slide 12
Symposia on VLSI Technology and Circuits
Optical Spin Readout
• Optical filter is required for green light rejection
• Photodiode is used to detect red fluorescence
Slide 13
Symposia on VLSI Technology and Circuits
• Measured isolation is 10 dB
Optical Excitation Filtering
Slide 14
Green light (532 nm)
Red light (700 nm)
Plasmonic Filter
800 nm
900 nm
FDTD simulated performance
Filter 3D structure
Filter cross section
Symposia on VLSI Technology and Circuits
Optical Fluorescence Readout
Slide 15
• Measured responsivity is 0.23 A/W
• 𝐏𝐄𝐝𝐝𝐲 ∝ ∝ ∝ ∝ L ∝ 𝐋𝟑
• 2×2 diode → 𝐏𝐄𝐝𝐝𝐲 ∝ 4 × ∝𝐋𝟑
𝟐• Cuts the losses in anode and cathode
• n×n diode → 𝐏𝐄𝐝𝐝𝐲 ∝𝐋𝟑
𝐧
P+ N-well Photo-diode
Symposia on VLSI Technology and Circuits Slide 16
• Introduction• CMOS Based Quantum Magnetometer
– System Architecture – Microwave Signal Generation– Optical Excitation Filtering – Optical Fluorescence Readout
• Experimental Results – Measurement Results Using Layer of Nano-Diamonds– Measurement Results Using Bulk Diamond
• Conclusion
Outline
Symposia on VLSI Technology and Circuits
Passivation Layer Removal
Slide 17
• Background fluorescence is emitted from the passivation (silicon nitrite) layer
• Reactive ion etching (RIE) for passivation layer removal
Before etching After etching
Fluorescence Intensity
Fluorescence Intensity
250 µm 250 µm
Symposia on VLSI Technology and Circuits
Nano-Diamonds Deposition
Slide 18
• Deposition of diamond nano-crystals solution
Before deposition After deposition & evaporation
250 µm 250 µm
Symposia on VLSI Technology and Circuits
• Sensitivity: 𝐂𝐖𝟏
𝜸
𝛔𝚫𝛎
𝐂
where γ = = 2.8 MHz/Gauss, σ ≡ Std. dev., Δν ≡ Linewidth, C ≡ Contrast, t ≡ Integration Time
Nano-Diamonds Measurement Results
Slide 19
Symposia on VLSI Technology and Circuits
Bulk Diamond Measurement Results
Slide 20
• Sensitivity: 𝐂𝐖𝟏
𝛄
𝛔
𝐦
where γ = = 2.8 MHz/Gauss, σ ≡ Std. dev., m , t ≡ Integration Time
Symposia on VLSI Technology and Circuits
Bulk Diamond Measurement Results
Slide 21
Symposia on VLSI Technology and Circuits Slide 22
• Introduction• CMOS Based Quantum Magnetometer
– System Architecture – Microwave Signal Generation– Optical Excitation Filtering – Optical Fluorescence Readout
• Experimental Results – Measurement Results Using Layer of Nano-Diamonds– Measurement Results Using Bulk Diamond
• Conclusion
Outline
Symposia on VLSI Technology and Circuits
Performance Summary
Slide 23
SensitivityFormfactor
Sensing area
Optical isolation
Vector meas.
Technology
73𝛍𝐓
𝐇𝐳
~ 1 𝟑
** 50 μm ×50 μm
10 dBNo65nm CMOSThis work
(Nano-diamonds)
2.5 𝛍𝐓
𝐇𝐳
~ 1 𝟑
**50 μm ×50 μm
20 dBYes65nm CMOSThis work
(Bulk Diamond)
0.29 𝐧𝐓
𝐇𝐳 ~ 1 𝟑
1 mm ×1mm
>60 dBYesDiscretedevices
Nature physics(2015) *
*Clevenson, et al. Nature Physics 2015** Does not include LASER
Symposia on VLSI Technology and Circuits
Conclusion
Slide 24
• Combines the advantages of CMOS and NV center in diamond in a small form factor
• Couples tightly the CMOS components with NV qubits• Offers on-chip spin state readout
• Easy integration of control logic • Less IOs• Closed-loop feedback between spin-manipulation and readout
• Enables compact and scalable advanced quantum systems.
