Hybrid Qubit gates in circuit QED: A scheme for quantum bit encoding and information processing

TL;DR

This paper proposes a hybrid quantum gate scheme in circuit QED using superconducting qubits and electromagnetic field states, enabling quantum information storage and entanglement generation with current technology.

Contribution

It introduces a novel hybrid two-qubit gate encoding combining solid-state qubits and field states, and explores entanglement generation via external magnetic pulses.

Findings

Encoding shows robustness against dissipative effects

Efficient quantum information storage demonstrated

Entanglement between qubits and field achieved

Abstract

Solid state superconducting devices coupled to coplanar transmission lines offer an exquisite architecture for quantum optical phenomena probing as well as for quantum computation implementation, being the object of intense theoretical and experimental investigation lately. In appropriate conditions the transmission line radiation modes can get strongly coupled to a superconducting device with only two levels -for that reason called artificial atom or qubit. Employing this system we propose a hybrid two-quantum bit gate encoding involving quantum electromagnetic field qubit states prepared in a coplanar transmission line capacitively coupled to a single charge qubit. Since dissipative effects are more drastic in the solid state qubit than in the field one, it can be employed for storage of information, whose efficiency against the action of an ohmic bath show that this encoding can be readily implemented with present day technology. We extend the investigation to generate entanglement between several solid state qubits and the field qubit through the action of external classical magnetic pulses.