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2. Quantum Optical Sensing. Single-mode optical interferometrysemiclassical theory: shot-noise limited performancequantum theory: coherent-state versus squeezed-state operationQuantum phase measurementSusskind-Glogower positive operator-valued measurement two-mode phase measurement: N00N-st
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1. October 1, 2007 Quantum Optical Sensing: Single Mode, Multi-Mode, and Continuous Time Jeffrey H. Shapiro
2. 2 Quantum Optical Sensing Single-mode optical interferometry
semiclassical theory: shot-noise limited performance
quantum theory: coherent-state versus squeezed-state operation
Quantum phase measurement
Susskind-Glogower positive operator-valued measurement
two-mode phase measurement: N00N-state performance
two-mode phase measurement with guaranteed precision
Continuous-time optical sensing
semiclassical theory: shot-noise limited broadband performance
quantum theory: what are the ultimate limits?
Conclusions
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6. 6 Single-Mode Number and Phase Wave Functions Single-mode field with annihilation operator
Number kets and phase kets
Number-ket and phase-ket state representations
Fourier transform relation
7. 7 Susskind-Glogower Phase Measurement Susskind-Glogower (SG) phase operator
SG positive operator-valued measurement (POVM)
SG-POVM probability density function
8. 8 Two-Mode Phase Measurement Signal and conjugate modes:
A pair of commuting observables:
When conjugate mode is in its vacuum state, measurement yields outcome with the SG-POVM probability density
BUT other behavior is possible when signal and conjugate are entangled
9. 9 N00N-State Phase Measurement Phase-conjugate interferometer with measurement
and N00N-state source
Phase-measurement probability density function
10. 10 Phase Measurement with Guaranteed Precision Phase-conjugate interferometer with measurement
and N00N-state sum
Optimum phase-measurement probability density function
11. 11 Performance Comparison for ? = 0 and N = 50 Phase-conjugate interferometry Two-mode measurement
12. 12 Continuous-Time Coherent-State Vibration Sensing Multi-bounce interrogation of vibrating mirror
Coherent-state source and heterodyne detection receiver
gives instantaneous frequency swing
Work in the wideband frequency modulation (WBFM) regime
13. 13 Continuous-Time Coherent-State Vibration Sensing Above-threshold WBFM reception requires
Above-threshold WBFM rms velocity error is
beating behavior seen earlier for nonclassical light
is the average number of detected signal photons in the vibration-signature bandwidth
Because classical light is used, loss degradation is graceful!
14. 14 Can Classical Light Do Even Better than 1/N3/2? Pulse-frequency modulation analog communication
transmitted as a coherent state and received by heterodyning
Cramr-Rao bound on rms error in estimate is
Cramr-Rao-bound performance prevails when
With exponential bandwidth expansion, goes down exponentially with increasing
15. 15 Towards the Ultimate Quantum Limit The Fourier duality between the number kets and phase kets for a single-mode field suggests that we seek a similar duality for continuous time
For unity quantum efficiency continuous-time direct detection the measurement eigenkets are known:
produces a photocount waveform on with counts at (and only at)
A suitable Fourier transform of this state may guide us to the ultimate quantum measurement for instantaneous frequency
16. 16 Conclusions Single-mode interferometric phase measurements
standard quantum limit achieved by coherent states
Heisenberg limit achieved by squeezed states
Two-mode phase measurements
Heisenberg limit achieved by N00N states
guaranteed precision at Heisenberg limit achieved by N00N sum
The BAD news
highly squeezed states and high-order N00N states hard to generate
nonclassical-state phase sensors do not degrade gracefully with loss
The GOOD news
continuous-time, coherent-state, wideband systems may offer superior performance and are robust to loss effects
theorists still have some fundamental quantum limits to determine