Temperature Selective Thermometry with Sub‐Microsecond Time Resolution Using Dressed‐Spin States in Diamond
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2021-09-16 |
| Journal | Advanced Quantum Technologies |
| Authors | Jiwon Yun, Kiho Kim, Sungjoon Park, Dohun Kim |
| Institutions | Seoul National University |
| Citations | 6 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This research presents a novel quantum thermometry scheme utilizing microwave-dressed spin states in nitrogen-vacancy (NV) centers in nanodiamonds, achieving high spatiotemporal resolution while maintaining robustness against external magnetic field fluctuations.
- Core Value Proposition: Achieves selective sensitivity to temperature changes, decoupling the measurement from magnetic field variations, which is a critical limitation in conventional NV thermometry.
- High Temporal Resolution: Demonstrated a sub-microsecond temporal resolution of 48 ns, enabling the imaging of fast transient thermal processes in nanoelectronic devices.
- Robustness: The dressed-spin state basis provides natural tolerance, limiting the systematic temperature error to 0.1 K under external magnetic field fluctuations up to 2 G.
- Sensitivity: Achieved a thermal sensitivity of 3.7 K·Hz-1/2 using ensemble NV centers in nanodiamonds on a coplanar waveguide (CPW).
- Methodology: Combines the dressed-state optically detected magnetic resonance (DS-ODMR) method with a continuous pump-probe sequence and a robust six-point frequency measurement technique.
- Practical Application: Favorable for time-resolved nanoscale quantum sensing and temperature imaging in complex environments, such as biological systems or nanoelectronics with fluctuating currents.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Thermal Sensitivity (Measured) | 3.7 | K·Hz-1/2 | Ensemble NV centers in nanodiamonds |
| Shot-Noise Limited Sensitivity | 2.5 | K·Hz-1/2 | Theoretical limit for the NV ensemble used |
| Temporal Resolution | 48 | ns | Achieved via 3-bin box averaging (16 ns bins) |
| Spatial Resolution (Demonstrated) | 10 | µm | Distance between measured nanodiamond ensembles |
| Magnetic Field Robustness | 2 | G | Maximum external magnetic field fluctuation tolerated |
| Systematic Temperature Error | 0.1 | K | Error induced by 2 G magnetic field fluctuation |
| Heating Microwave Frequency | 2.8 | GHz | Carrier frequency of the heating pulse |
| Heating Microwave Power | 48 | dBm | Applied to the CPW for Joule heating |
| Heating Pulse Duration | 3 | µs | Duration used to induce temperature change |
| Nanodiamond Diameter (Average) | 100 | nm | Adamas nanodiamonds used |
| Bare Spin State Sensitivity (dD/dT) | 74 | kHz·K-1 | Sensitivity of zero-field splitting to temperature |
| DS-ODMR Linewidth (Γ) | 11.5 | MHz | Used for six-point measurement calculation |
| Ambient Temperature (T∞) | 26 | °C | Boundary condition for heat transfer simulation |
Key Methodologies
Section titled “Key Methodologies”The experiment relies on a continuous wave optically detected magnetic resonance (cw-ODMR) scheme adapted to microwave-dressed spin states (DS-ODMR) for selective temperature sensing.
- Sample Preparation: Nanodiamonds (100 nm average diameter) containing ensemble NV centers were dispersed onto a gold Coplanar Waveguide (CPW) fabricated on a cover glass substrate.
- Spin State Preparation (Dressed Basis):
- Two continuous microwaves (MW1 and MW2) were applied simultaneously, resonant to the |0> ↔ |+1> and |0> ↔ |-1> transitions, respectively.
- The microwaves shared the same Rabi frequency (Ω) to move the system into the double rotating frame, creating the dressed-spin eigenstates (|0>d, |Bright>d, |Dark>d).
- This dressed basis ensures that the measured frequency shift (δD) is primarily proportional to the temperature-dependent zero-field splitting (D(T)), making it robust against magnetic field fluctuations (δBz and δBx).
- Heating Mechanism (Pump): A high-power microwave pulse (MW3, 2.8 GHz, 48 dBm) was applied to the CPW signal line, inducing localized Joule heating in the gold conductor.
- Time-Resolved Measurement (Probe):
- A continuous pump-probe sequence was used, where the green laser and probe microwaves (MW1, MW2) were applied continuously.
- The center frequency of the two probe microwaves was modulated stepwise across six distinct frequencies (fA to fF) within a 60 µs total period (10 µs allocated per frequency point).
- This six-point measurement method was used to calculate the frequency shift (δfavg) while compensating for fluctuations in fluorescence contrast, linewidth (Γ), and long-term drift.
- Detection and Synchronization:
- Emitted fluorescence was measured continuously using a time-tagged photon counting module with a 16 ns bin size.
- The frequency shifting, heating pulse envelope, and photon counting were synchronized using a common trigger to achieve time-resolved data stacking.
- Data Processing: Fluorescence data was converted into temperature change (ΔT) using the derived six-point formula (Equation 5). A 48 ns time resolution was achieved by box averaging 3 bins.
Commercial Applications
Section titled “Commercial Applications”The robust, high-speed thermometry technique developed using dressed-spin NV centers is highly relevant for advanced engineering and scientific fields where precise thermal management and sensing under complex electromagnetic conditions are required.
- Nanoelectronics and Microchip Imaging:
- Time-resolved thermal imaging of integrated circuits (ICs) and nanoelectronic devices (e.g., graphene, transistors).
- Characterization of transient heat dissipation and local hot spots before thermal equilibrium is reached.
- Sensing temperature in environments where varying electric currents cause fluctuating local magnetic fields.
- Quantum Sensing and Metrology:
- Development of robust, selective quantum sensors that can simultaneously measure temperature and magnetic fields without cross-talk (when combined with independent magnetometry methods).
- Applications in chip-scale imaging where both selectivity and sensitivity are paramount.
- Biomedical and Biological Imaging:
- Measuring localized temperature changes in living cells or biological tissues induced by external stimuli (e.g., microwave heating or metabolic activity).
- The method’s robustness to arbitrary external magnetic fields simplifies application in complex biological settings where aligning the field to individual nanodiamond axes is impractical.
- Materials Science and Thermal Property Characterization:
- Investigating the thermal properties and heat transfer dynamics of novel materials, especially those with high thermal conductivity (like gold CPWs demonstrated here).
- Characterization of transient thermal processes in various nanoscale systems.
View Original Abstract
Abstract Versatile nanoscale sensors that are susceptible to changes in a variety of physical quantities often exhibit limited selectivity. This paper reports a novel scheme based on microwave‐dressed spin states for optically probed nanoscale temperature detection using diamond quantum sensors, which provides selective sensitivity to temperature changes. By combining this scheme with a continuous pump-probe scheme using ensemble nitrogen‐vacancy centers in nanodiamonds, a sub‐microsecond temporal resolution with thermal sensitivity of 3.7 that is insensitive to variations in external magnetic fields on the order of 2 G is demonstrated. The presented results are favorable for the practical application of time‐resolved nanoscale quantum sensing, where temperature imaging is required under fluctuating magnetic fields.