Conditional Phase Shift for Quantum CCNOT Operation

TL;DR

This paper proposes a method for implementing a quantum CCNOT gate using cavity QED, utilizing conditional phase shifts and measurement-induced evolution, and also demonstrates generating EPR pairs from separable states.

Contribution

It introduces a new approach to quantum phase gate implementation in cavity QED using Kraus operators and conditional evolution without quantum jumps, and shows how to generate EPR pairs.

Findings

Conditional phase shift enables quantum CCNOT operation.

Measurement-based evolution simplifies gate implementation.

EPR pairs can be generated from initial separable states.

Abstract

We suggest the improvement of description methods for quantum phase gate implementation in the cavity of QED configuration. Qubits are encoded into two lowest Fock state. Three qubit phase transformation is resulted from the interaction between Rydberg atom and three modes of cavity electromagnetic field. Evolution of conditional field states appearing after atom measurement is described by Kraus transformers. One of these operators is very convenient for phase gate implementation. We show that it corresponds to conditional evolution without quantum jumps. Also we describe cavity based generating EPR pair from certain initially disentangled state.