Quantum nonlinear spectroscopy of single nuclear spins

Abstract

Nonlinear spectroscopy is widely used for studying physical systems. Conventional nonlinear optical spectroscopy and magnetic resonance spectroscopy, which use classical probes such as electromagnetic waves, can only access certain types of correlations in a quantum system. The idea of quantum nonlinear spectroscopy was recently proposed to use quantum probes such as entangled photons to achieve sensitivities and resolutions beyond the classical limits. It is shown that quantum sensing can extract arbitrary types and orders of correlations in a quantum system by first quantum-entangling a sensor and the object and then measuring the sensor. Quantum sensing has been applied to achieve nuclear magnetic resonance (NMR) of single atoms and the second-order correlation spectroscopy has been adopted to enhance the spectral resolution. However, quantum nonlinear spectroscopy (i.e., the measurement of higher-order correlations) of single nuclear spins is still elusive. Here we demonstrate the extraction of fourth-order correlations of single nuclear spins that cannot be measured in conventional nonlinear spectroscopy, using sequential weak measurement via an atomic quantum sensor, namely, a nitrogen-vacancy center in diamond. We show that the quantum nonlinear spectroscopy provides fingerprint features to identify different types of objects, such as Gaussian noises, random-phased AC fields, and quantum spins, which would be indistinguishable in second-order correlations. The measured fourth-order correlation unambiguously differentiates a single nuclear spin and a random-phased AC field. This work constitutes an initial step toward the application of higher-order correlations to quantum sensing, to examining the quantum foundation (by, e.g., higher-order Leggett-Garg inequality), and to studying quantum many-body physics.

23 pages and 4 figures

References in corpus (9)

• Dynamical decoupling and noise spectroscopy with a superconducting flux qubit
• High-fidelity projective readout of a solid-state spin quantum register
• Sub-millihertz magnetic spectroscopy with a nanoscale quantum sensor
• Detection and control of individual nuclear spins using a weakly coupled electron spin
• Quantum sensing with arbitrary frequency resolution
• Robust dynamical decoupling for quantum computing and quantum memory
• Nuclear spin pair coherence in diamond for atomic scale magnetometry
• Quantum many-body theory for electron spin decoherence in nanoscale nuclear spin baths
• Signatures of quantum behavior in single-qubit weak measurements

Cited by in corpus (6)

• Review: Quantum Metrology and Sensing with Many-Body Systems
• Anomalous noise spectra in a spin-exchange-relaxation-free alkali-metal vapor
• Computing n-time correlation functions without ancilla qubits
• Quantum illumination with noisy probes: Conditional advantages of non-Gaussianity
• Making Every Photon Count: A Quantum Polyspectra Approach to the Dynamics of Blinking Quantum Emitters at Low Photon Rates Without Binning
• Unlocking Heisenberg Sensitivity with Sequential Weak Measurement Preparation