Quantum Sensor Spin Readout via Excited State Lifetime
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Solution Overview
Problem
Current spin state readout methods based on nitrogen vacancy (NV) centers in diamond face challenges such as low sensitivity and accuracy due to laser power drifts and inefficient signal generation, particularly in magnetic field sensing schemes that rely on excited state lifetime measurements.
Innovation Solution
A spin state readout device comprising a pumping unit for polarizing the spin state, a probing unit for exciting the NV center with short pulse lasers, a signal receiving unit for converting fluorescence into electrical signals, and a timing unit to measure the excited state lifetime, along with a manipulating unit for introducing microwave pulses to control the spin state, thereby reducing errors and improving sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ODMR spin state readout scheme based on fluorescence intensity is used, then the spin state can be measured, but the measurement precision deteriorates due to laser power drifts causing readout errors
Solution Approach 1:
The patent introduces a timing unit as an intermediary that measures the excited state lifetime of the NV center. Instead of directly measuring fluorescence intensity which is sensitive to laser power drift, the system uses lifetime measurement as an intermediary parameter that is independent of laser power fluctuations, thereby resolving the contradiction between measurement capability and measurement precision
Solution Approach 2:
The patent changes the measurement parameter from fluorescence intensity to excited state lifetime. By measuring the temporal decay of the excited state rather than the intensity of emitted photons, the system eliminates sensitivity to laser power drift while maintaining the ability to read out spin state information through the spin-dependent lifetime difference
2Measurement precision
If the magnetic field sensing scheme based on excited state lifetime of single NV center is used, then the spin state can be detected, but the productivity deteriorates due to low signal generation efficiency and long measurement time
Solution Approach 1:
The patent implements continuous spin polarization using a pumping unit that continuously drives NV centers into the spin 0 state before each measurement cycle. This continuous preparation ensures that each probe pulse encounters a maximally polarized spin population, thereby maximizing the signal generation efficiency and reducing the number of measurement cycles required
Solution Approach 2:
The patent uses periodic probe pulses to repeatedly measure the excited state lifetime. By optimizing the pulse repetition rate and using multiple measurements per polarization cycle, the system accumulates sufficient signal statistics efficiently, improving productivity while maintaining measurement precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution enhances the sensitivity and accuracy of spin detection by doubling the signal photon productivity and reducing errors caused by laser power drifts, thus improving the practicality of NV center-based quantum sensing and measurement technologies.
Implementation Method 1
a pumping unit configured to emit a first laser to the quantum sensor to polarize the spin state of the quantum sensor
Implementation Method 2
a probing unit configured to emit a second laser to the quantum sensor to make the spin-polarized quantum sensor in an excited state
Implementation Method 3
a signal receiving unit configured to receive fluorescence photons emitted from the quantum sensor
Implementation Method 4
convert optical signals into electrical signals
Implementation Method 5
a timing unit coupled to the probing unit and the signal receiving unit and configured to time an excited state lifetime of the quantum sensor
Implementation Method 6
a manipulating unit configured to introduce microwave pulses to the quantum sensor to manipulate the electron spin state of the quantum sensor
Data Source
AI summary
A spin state readout device of a quantum sensor. The quantum sensor has spin-manipulable electrons. The spin state readout device includes: a pumping unit configured to emit a first laser to the quantum sensor to polarize the electron spin state of the quantum sensor; a probing unit configured to emit a second laser to the quantum sensor to make the spin-polarized quantum sensor in an excited state; a signal receiving unit configured to receive fluorescence photons emitted from the quantum sensor and convert optical signals into electrical signals; and a timing unit coupled to the probing unit and the signal receiving unit and configured to time an excited state lifetime of the quantum sensor. The spin state readout device of the quantum sensor provided can reduce spin state reading errors caused by laser power drifts, system signal collection efficiency drifts and the like.