A quantum sensor is a device that exploits quantum correlations, such as quantum entanglement, to achieve a sensitivity or resolution that is better than can be achieved using only classical systems.
A quantum sensor can measure the effect of the quantum state of another system on itself. The mere act of measurement influences the quantum state and alters the probability and uncertainty associated with its state during measurement.
The Defense Advanced Research Projects Agency has recently launched a research program in optical quantum sensors that seeks to exploit ideas from quantum metrology and quantum imaging, such as quantum lithography and the NOON state, in order to achieve these goals with optical sensor systems such as lidar.
A good example of an early quantum sensor is an APD avalanche photodiode such as the AD500-8 TO52S1 as these have been used to detect entangled photons and in fact with additional cooling and sensor improvements can be used where PMTs once ruled the market such as medical imaging. These are also now being used by First Sensor in the form of 2-D and even 3-D stacked arrays as a direct replacement for conventional sensors based on silicon diodes.
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- BROAD AGENCY ANNOUNCEMENT (BAA) 07-22 Quantum Sensors
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