Remote entanglement via two mode squeezed light

Remotely entangling qubits which do not interact directly is very desirable for quantum information processing. One method for remote entanglement is to read out two qubits in parallel with their outputs entering the signal and idler mode of a phase-preserving amplifier. The amplifier squeezes away which-path information and can project the qubits into a Bell state. However, this measurement also produces an outcome-dependent phase kick on the qubits’ state. Thus, losses and inefficient amplification can prevent the generation of entangled states [1, 2]. However, we have recently demonstrated a new scheme which uses two-mode squeezed light (TMSL) in an interferometer formed by two phase-preserving amplifiers to measure a qubit. We find that the phase back-action of TMSL measurement alters the phase back-action relative to coherent readout, depending on the amplifiers’ relative phase. Here we present a two qubit, TMSL interferometric entangling readout. We will show how TMSL affects the back-action of the entangling readout and discuss the prospects for the use of TMSL to make the scheme more tolerant of hardware imperfections.

[1] Silveri et al, PRA 93, 062310 (2016)
[2] Zalys-Gellar et al, Arxiv: 1803.01275 (2018)