A quantum logic gate between a solid-state quantum bit and a photon

TL;DR

This paper demonstrates a quantum logic gate between a solid-state quantum dot qubit and a photon, enabling fast, conditional polarization control crucial for scalable quantum networks and computing.

Contribution

It experimentally realizes a solid-state quantum logic gate using a quantum dot coupled to a nano-cavity, achieving ultrafast, coherent control of photon polarization.

Findings

Successful implementation of a cNOT gate between a quantum dot and a photon

Conditional polarization flip occurs on picosecond timescales

Advances towards scalable solid-state quantum networks

Abstract

Integrated quantum photonics provides a promising route towards scalable solid-state implementations of quantum networks, quantum computers, and ultra-low power opto-electronic devices. A key component for many of these applications is the photonic quantum logic gate, where the quantum state of a solid-state quantum bit (qubit) conditionally controls the state of a photonic qubit. These gates are crucial for development of robust quantum networks, non-destructive quantum measurements, and strong photon-photon interactions. Here we experimentally realize a quantum logic gate between an optical photon and a solid-state qubit. The qubit is composed of a quantum dot (QD) strongly coupled to a nano-cavity, which acts as a coherently controllable qubit system that conditionally flips the polarization of a photon on picosecond timescales, implementing a controlled-NOT (cNOT) gate. Our results represent an important step towards solid-state quantum networks and provide a versatile approach for probing QD-photon interactions on ultra-fast timescales.