Balancing efficiencies by squeezing in realistic eight-port homodyne detection



: Pellonpää Juha-Pekka, Schultz Jussi, Paris Matteo G A

Publisher: AMER PHYSICAL SOC

: 2011

: Physical Review A

: PHYSICAL REVIEW A

: PHYS REV A

: ARTN 043818

: 4

: 83

: 4

: 7

: 1050-2947

DOI: https://doi.org/10.1103/PhysRevA.83.043818(external)

: https://research.utu.fi/converis/portal/Publication/3790436(external)


We address measurements of covariant phase observables (CPOs) by means of realistic eight-port homodyne detectors. We do not assume equal quantum efficiencies for the four photodetectors and investigate the conditions under which the measurement of a CPO may be achieved. We show that balancing the efficiencies using an additional beam splitter allows us to achieve a CPO at the price of reducing the overall effective efficiency, and prove that it is never a smearing of the ideal CPO achievable with unit quantum efficiency. An alternative strategy based on employing a squeezed vacuum as a parameter field is also suggested, which allows one to increase the overall efficiency in comparison to the passive case using only a moderate amount of squeezing. Both methods are suitable for implementation with current technology.

Last updated on 2024-26-11 at 13:02