Entanglement-enhanced sensing using a chain of qubits with always-on nearest-neighbor interactions

TL;DR

This paper proposes a quantum sensing scheme using a chain of qubits with always-on interactions, leveraging quantum domino dynamics to generate entanglement without complex control, achieving sensitivity beyond the standard quantum limit.

Contribution

It introduces a practical entanglement-enhanced sensing method that operates with always-on interactions and minimal control, simplifying implementation compared to traditional approaches.

Findings

Achieves sensitivity beyond the standard quantum limit.

Operates effectively with realistic decoherence.

Does not require switching interactions on and off.

Abstract

Quantum metrology is the use of genuinely quantum properties such as entanglement as a resource to outperform classical sensing strategies. Typically, entanglement is created by implementing gate operations or inducing many-body interactions. However, existing sensing schemes with these approaches require accurate control of the probe system such as switching on and off the interaction among qubits, which can be challenging for practical applications. Here, we propose an entanglement-enhanced sensing scheme with an always-on nearest-neighbor interaction between qubits. We adopt the transverse field Ising chain as the probe system, making use of the so-called quantum domino dynamics for the generation of the entangled states. In addition to the advantage that our scheme can be implemented without controlling the interactions, it only requires initialization of the system, projective measurements on a single qubit, and control of the uniform magnetic fields. We can achieve an improved sensitivity beyond the standard quantum limit even under the effect of realistic decoherence.