schrodinger cat state quantum breakthrough

Long-Lived Schrodinger's Cat State Reaches Heisenberg-Limited Precision

Introduction

Researchers from the University of Science and Technology of China (USTC), directed by Prof. Lu Zhengtian and Researcher Xia Tian, achieved a Schrödinger-cat state with a minute-scale lifetime through optically trapped cold atoms. The study, enhancing quantum metrology sensitivity, appeared in Nature Photonics.

The Role of Particle Spin in Quantum Metrology

Quantum Metrology and Magnetic Field Detection

Particle spin plays a crucial role in quantum metrology, serving as an effective probe for detecting magnetic fields, inertial effects, and diverse physical phenomena, while also enabling exploration of physics beyond the Standard Model.

High-Spin Schrödinger-Cat State

The high-spin Schrödinger-Cat state, characterized by a superposition of two maximally separated spin states, enhances spin measurement capabilities. The high spin quantum number augments precession frequency signals, while cat states offer insensitivity to specific environmental noise, reducing measurement errors.

Challenges in Sustaining Coherence

Issues with Coherence over Time

One of the primary challenges in quantum metrology in sustaining the coherence of these states over extended timescales. The difficulty lies in maintaining stability while preserving the superposition states needed for high-precision measurements.

Experimental Setup and Methodology

Optical Lattice and ¹⁷³Yb Atoms

By confining ¹⁷³Yb atoms with a spin of 5/2 within an optical lattice, the researchers addressed this challenge. They used controlled laser pulses to generate nonlinear light shifts, successfully preparing a superposition state of spin projections +5/2 and -5/2.

Creation of the Schrödinger-Cat State

This state, known as the Schrödinger-Cat state, demonstrates heightened magnetic field sensitivity and identical light shifts within the opticla lattice, residing in a decoherence-free subspace. Consequently, it is resistant to intensity noise and spatial lattice variations.

Key Findings and Implications

Enhanced Coherence Time

Experimental observations revealed that the coherence time of this cat state surpassed 20 minutes. This extended coherence opens new possibilities for long-duration quantum measurements.

Heisenberg-Limited Precision

By employing Ramsey interferometry, the researchers demonstrated phase measurement sensitivity nearing the Heisenberg limit. This enduring Schrödinger-Cat state opens novel avenues for advancements in atomic magnetometry, quantum computing, and investigations into physics beyond the Standard Model.

Conclusion and Future Applications

Advancements in Quantum Technologies

This enduring Schrödinger-Cat state opens novel avenues for advancements in atomic magnetometry, quantum computing, and investigations into physics beyond the Standard Model.

Source

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