Sequential Measurements for Quantum-Enhanced Magnetometry in Spin Chain Probes.

Area of Science:

• Quantum Metrology
• Quantum Sensing
• Many-Body Physics

Background:

• Quantum sensors offer superior precision over classical sensors.
• Current quantum-enhanced sensitivity relies on superposition, entanglement, or specific system states.
• Existing methods often require complex initializations like entangled states or critical states.

Purpose of the Study:

• To introduce a novel approach for quantum-enhanced sensitivity in many-body probes.
• To achieve enhanced sensing precision without requiring prior entanglement.
• To utilize quantum measurement and wave function collapse for improved sensitivity.

Main Methods:

• A protocol involving a sequence of local measurements on a many-body probe.
• Measurements are performed regularly during the probe's evolution without reinitialization.
• The approach leverages the inherent nature of quantum measurement and wave function collapse.

Main Results:

• Sensing precision is enhanced beyond the standard quantum limit.
• The precision asymptotically approaches the Heisenberg limit with an increasing number of measurement sequences.
• The protocol demonstrates quantum-enhanced sensitivity without demanding prior entanglement.

Conclusions:

• A new, entanglement-free protocol enhances quantum sensing precision in many-body systems.
• The method utilizes local measurements and wave function collapse, simplifying initialization.
• This approach enables remote quantum sensing and achieves Heisenberg-limited precision.