Towards constructing a parity interferometer

Abstract

In continuous-variable quantum information [1], it is important to characterize quantum states in order to verify the quality of the preparation and to test the output of protocols [2]. For this purpose, we apply the quantum-mechanical parity operator which enables the reconstruction of the phase-space representation of a quantum state [3,4]. However, the implementation of a parity measurement is a subtle issue as many existing schemes are restricted to the particular sets of states to be probed. In this talk, we present a scheme for parity measurements independent of the physical quantum system. In particular, we reveal the key components necessary for the construction of a parity interferometer. The output of our device measures the parity of a general initial state. We further exploit possible implementations and discuss limitations in such experimental arrangements.

[1] A. L. Braunstein und A. K. Pati, Quantum Information with Continuous Variables (Kluwer Academic Publishers, Dordrecht, 2001). [2] A. I. Lvovsky and M. G. Raymer, Rev. Mod. Phys. 81, 299 (2009). [3] A. Royer, Phys. Rev. A 15, 449 (1977). [4] F. Ullinger, ’Interference effects in quadratic potentials’, Master’s thesis (Ulm University, Ulm, 2022).