Fast high-fidelity geometric quantum control with quantum brachistochrones

TL;DR

This paper demonstrates a method for fast, high-fidelity geometric quantum control using quantum brachistochrones, achieving significant speedups and fidelity improvements in quantum gates on diamond spin systems, enabling enhanced quantum sensing.

Contribution

The authors experimentally implement the most brachistochrone-based geometric control, achieving faster and more accurate quantum gates compared to conventional methods, and apply these to quantum metrology.

Findings

Single-qubit gates with >99.2% fidelity achieved in 74.9% less time

Two-qubit gates with >96.5% fidelity demonstrated

Enhanced measurement bandwidth and sensitivity in quantum sensing

Abstract

We experimentally demonstrate fast and high-fidelity geometric control of a quantum system with the most brachistochrone method on hybrid spin registers in diamond. Based on the time-optimal universal geometric control, single geometric gates with the fidelities over 99.2% on the spin state of nitrogen-vacancy center are realized with average durations shortened by 74.9%, comparing with conventional geometric method. The fidelity of the fast geometric two-qubit gate exceeds 96.5% on the hybrid spin registers. With these fast high-fidelity gates available, we implement quantum entanglement-enhanced phase estimation algorithm and demonstrate the Heisenberg quantum limit at room-temperature. By comparing with the conventional geometric circuit, the measurement bandwidth and sensitivity is enhanced by 3.5 and 2.9 times. Hence, our results show that high-fidelity quantum control based on a fast geometric route will be a versatile tool for broad applications of quantum information processing in practice.