Processing quantum information in a hybrid topological qubit and superconducting flux qubit system

Abstract

A composite system of Majorana-hosted semiconductor nanowire and superconducting flux qubit is investigated. It is found that the coupling between these two subsystems can be controlled electrically, supplying a convenient method to implement π/8 phase gate of a Majorana-based topological qubit. We also present a scheme to transfer information from the flux qubit to the topological qubit using Landau-Zener transition. In addition, a structure named top-flux-flux is proposed to retrieve the information stored in the topological qubit. With the demonstration of the entanglement of two topological qubits, it is very promising to do quantum information process with this hybrid system.

Minimal circuit for a flux-controlled Majorana qubit in a quantum spin-Hall insulator

“…The key ingredients of the top-transmon [9] are: (1) a charge qubit to couple Majorana zero-modes; (2) a flux-controlled Josephson junction to switch the Coulomb coupling on and off ; (3) a microwave resonator to read out the Majorana qubit. There exist many alternative proposals to operate on Majorana qubits [22][23][24][25][26][27][28][29][30][31][32][33][34][35], including an alternative hybrid design that uses a flux qubit instead of a charge qubit [36][37][38][39][40][41][42].…”

Interfacing a Topological Qubit with a Spin Qubit in a Hybrid Quantum System

“…These two states are denoted asn x =f † xfx = 0 or 1 (x = l, r), with par-ityP x = (−1)f † xf x = ±1. As braiding operations can not change the total parityP =P lPr of the system, four MFs are usually needed to define a logical topological qubit [24,30]. We now define the topological qubit in the odd parity subspace, and obtain |φ T P = c 1 |0 l |1 r + c 2 |1 l |0 r .…”

“…To overcome these problems, several types of hybrid quantum architectures coupling the topological qubits to the conventional ones have been proposed. One potential route is controlling the microscopic wave function of the superconductors, which allows the strong coupling between a topological qubit and a flux qubit, or a mechanical oscillator [24][25][26]. Other promising schemes include utilizing the Aharonov-Casher effect [27][28][29], or the fractional Josephson effect [30][31][32].…”

Robust interface between flying and topological qubits

“…One possible alternative scenario is to use the hybrid architecture between topological and conventional qubits, which can consolidate the advantages of both systems -the topological qubits are robust against perturbations * zyxue@scnu.edu.cn † skylark.gong@gmail.com ‡ zwang@hku.hk while the conventional qubits can be used to perform universal quantum computation via coherent control. So far, many schemes have been proposed to interface topological and conventional qubits [24][25][26][27][28][29][30][31][32][33], with most being used to measure the topological qubits. Generally, there is essentially an obstacle for the realization of strong coupling between conventional and topological qubits, that is, the energy mismatch effect.…”