Super-Sensitive Quantum Metrology with Many-Particle Separable State*

Super-sensitive phase measurement is central to quantum metrology. Two well-known methods of obtaining phase super-resolution involve the use of the squeezed state [1] and many-particle entangled state [2,3]. We present a super-resolving and super-sensitive phase measurement scheme that does not require either a squeezed state or an entangled state. We instead use a many-particle separable state to probe the phase and we retrieve the phase from a single-particle interference pattern. Our method is based on a recently introduced many-particle interferometric scheme [4] and it applies to both bosons and fermions [5]. A striking feature of our scheme is that the particles used to probe the phase are not required to be detected.


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[2] Yurke et al., “SU(2) and SU(1,1) Interferometers,” Phys. Rev. A 33, 4033 (1986).
[3] Dowling, “Correlated input-port, matter-wave interferometer: Quantum-noise limits to the atom-laser gyroscope,” Phys. Rev. A 57, 4736 (1998).
[4] Lahiri, “Many-particle interferometry andentanglement by path identity,” Phys. Rev. A 98, 033822 (2018).
[5] Lahiri and Erhard, “Super-Sensitive Quantum Metrology with Separable States,” arXiv:2005.09247 (2020).