Interferometric robust preparation of maximally entangled states of identical particles

 Interferometric robust preparation of maximally entangled states of identical particles

Seminar author:Matteo Piccolini

Event date and time:06/22/2023 04:00:pm

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Realistic preparations of entangled states are hindered by the unavoidable interaction with the surrounding environment, whose noisy action is detrimental for the quantum correlations within the system. For this reason, many different techniques to circumvent the problem have been proposed over time.
We present a scheme, valid for both bosons and fermions, to prepare maximally entangled states of two identical qubits in a way that is robust under the effect of any type of local noise, both quantum and classical. Considering linear optics operations, the procedure utilizes an externally-activated depolarizing channel and a pseudospin-insensitive, non-absorbing, parity check detector in an iterative process with probability which converges exponentially to one with the number of repetitions. The scheme is thus asymptotically deterministic. Distributing the particles over two distinct spatial modes, we further show that the elements of the basis composed of maximally entangled states can be divided in two sets according to an equivalence based on passive optical transformations. We demonstrate that the parity check detector can be used to connect these two sets of states.

The proposed procedure can be ultimately exploited to prepare any pure state of two identical qubits which are maximally entangled in either the internal degree of freedom (Bell states) or the spatial mode (NOON states).