Optimal Quantum-Enhanced Interferometry

Abstract

We analyze the ultimate bounds on the phase sensitivity of an interferometer, given the constraint that the state input to the interferometer's initial 50:50 beamsplitter $B$ is a product state of the two input modes. Requiring a product state is a natural restriction: if one were allowed to input an arbitrary, entangled two-mode state $|\Xi ⟩$ to the beamsplitter, one could generally just as easily input the state $B|\Xi ⟩$ directly into the two modes after the beamsplitter, thus rendering the beamsplitter unnecessary. We find optimal states for a fixed photon number and for a fixed mean photon number.

References in corpus (4)

• Quantum Optical Metrology -- The Lowdown on High-N00N States
• Mach-Zehnder Interferometry at the Heisenberg Limit with coherent and squeezed-vacuum light
• Experimental demonstration of phase measurement precision beating standard quantum limit by projection measurement
• Robustness of Heisenberg-limited interferometry with balanced Fock states

Cited by in corpus (4)

• Quantum metrology with unitary parametrization processes
• Quantum correlations in optical metrology: Heisenberg-limited phase estimation without mode entanglement
• Fisher information of a squeezed-state interferometer with a finite photon-number resolution
• Ultimate phase estimation in a squeezed-state interferometer using photon counters with a finite number resolution