Quantum Gates Between Distant Qubits via Spin-Independent Scattering

TL;DR

This paper proposes a method to create entangling quantum gates between distant qubits using spin-independent scattering in 1D systems, offering an alternative to photonic mediators for scalable quantum computing.

Contribution

It introduces a novel scheme for entangling distant qubits via scattering in 1D confinement, applicable to both wave-guide and lattice setups, with analysis of feasibility and control requirements.

Findings

Entangling gates can be implemented through spin-independent scattering.

The scheme works for both fermionic and bosonic particles in 1D confinement.

Gate quality depends on momentum distributions and initial distances.

Abstract

We show how the spin independent scattering of two initially distant qubits, say, in distinct traps or in remote sites of a lattice, can be used to implement an entangling quantum gate between them. The scattering takes place under 1D confinement for which we consider two different scenarios: a 1D wave-guide and a tight-binding lattice. We consider models with contact-like interaction between two fermionic or two bosonic particles. A qubit is encoded in two distinct spins (or other internal) states of each particle. Our scheme enables the implementation of a gate between two qubits which are initially too far to interact directly, and provides an alternative to photonic mediators for the scaling of quantum computers. Fundamentally, an interesting feature is that "identical particles" (e.g., two atoms of the same species) and the 1D confinement, are both necessary for the action of the gate. Finally, we discuss the feasibility of our scheme, the degree of control required to initialize the wave-packets momenta, and show how the quality of the gate is affected by momentum distributions and initial distance. In a lattice, the control of quasi-momenta is naturally provided by few local edge impurities in the lattice potential.