Multiplex-controlled phase gate with qubits distributed in a multi-cavity system

TL;DR

This paper proposes a scalable method to implement a multiplex-controlled phase gate across multiple cavities using qutrits, with potential for high-fidelity operation in various physical systems like atoms, NV centers, and superconducting circuits.

Contribution

It introduces a linear-in-n number of basic operations for multiqubit gates distributed in separate cavities, enabling fast and scalable quantum gate implementation.

Findings

Numerical simulations demonstrate high-fidelity three-qubit controlled phase gate.

The method is applicable to various physical systems including atoms and superconducting qutrits.

The required basic operations increase linearly with the number of qubits.

Abstract

We present a way to realize a multiplex-controlled phase gate of n-1 control qubits simultaneously controlling one target qubit, with n qubits distributed in n different cavities. This multiqubit gate is implemented by using n qutrits (three-level natural or artificial atoms) placed in n different cavities, which are coupled to an auxiliary qutrit. Here, the two logic states of a qubit are represented by the two lowest levels of a qutrit placed in a cavity. We show that this n-qubit controlled phase gate can be realized using only 2n+2 basic operations, i.e., the number of required basic operations only increases linearly with the number n of qubits. Since each basic operation employs the qutrit-cavity or qutrit-pulse resonant interaction, the gate can be fast implemented when the number of qubits is not large. Numerical simulations show that a three-qubit controlled phase gate, which is executed on three qubits distributed in three different cavities, can be high-fidelity implemented by using a circuit QED system. This proposal is quite general and can be applied to a wide range of physical systems, with atoms, NV centers, quantum dots, or various superconducting qutrits distributed in different cavities. Finally, this method can be applied to implement a multiqubit controlled phase gate with atoms using a cavity. A detailed discussion on implementing a three-qubit controlled phase gate with atoms and one cavity is presented.