Elementary gates for quantum information with superposed coherent states

TL;DR

This paper introduces probabilistic methods using single photon subtractions to implement elementary quantum gates on qubits encoded in superposed coherent states, enabling large phase shifts with current technology.

Contribution

It presents novel probabilistic schemes for quantum gates in the coherent state basis, suitable for near-term quantum information experiments.

Findings

Capable of achieving arbitrarily large phase shifts

Suitable for near-future quantum information tests

Uses single photon subtraction as a key operation

Abstract

We propose a new way of implementing several elementary quantum gates for qubits in the coherent state basis. The operations are probabilistic and employ single photon subtractions as the driving force. Our schemes for single-qubit phase gate and two-qubit controlled phase gate are capable of achieving arbitrarily large phase shifts with currently available resources, which makes them suitable for the near-future tests of quantum information processing with superposed coherent states.