Duality in entanglement of macroscopic states of light

Abstract

We investigate duality in entanglement of a bipartite multi-photon system generated from a coherent state of light. The system can exhibit polarization entanglement if the two parts are distinguished by their parity, or parity entanglement if the parts are distinguished by polarization. It was shown in [PRL 110, 140404 (2013)] that this phenomenon can be exploited as a method to test indistinguishability of two particles and it was conjectured that one can also test indistinguishability of macroscopic systems. We propose a setup to test this conjecture. Contrary to the previous studies using two-particle interference effect as in Hong-Ou-Mandel setup, our setup neither assumes that the tested state is composed of single particles nor requires that the total number of particles be fixed. Consequently the notion of entanglement duality is shown to be compatible with a broader class of physical systems. Moreover, by observing duality in entanglement in the above system one can confirm that macroscopic systems exhibit quantum behaviour. As a practical side, entanglement duality is a useful concept that enables adaptive conversion of entanglement of one degree of freedom (DOF) to that of another DOF according to varying quantum protocols.

Implementation of Traveling Odd Schrödinger Cat States in Circuit-QED

“…Because this method brings the very high fidelity to SCSs at small amplitudes, the amplification of the SCSs may be required for practical QI processing [15]. In addition, the traveling SCSs are also useful resource states for performing nonlocality tests [16,17] and for testing indistinguishability of macroscopic states [18]. The rapid development of superconducting circuit technology has shown the potential to provide a new platform for scalable quantum systems.…”

“…Because this method brings very high fidelity to SCSs at small amplitudes, the amplification of the SCSs may be required for practical QI processing [25,26]. In addition, the traveling SCSs are also useful resource states for performing nonlocality tests [27][28][29][30][31][32][33] and for testing indistinguishability of macroscopic states [34].…”