Nonequilibrium Spin Noise and Noise of Susceptibility

Abstract

We analyze out-of-equilibrium fluctuations in a driven spin system and relate them to the noise of spin susceptibility. In the spirit of the linear response theory we further relate the noise of susceptibility to a $4$-spin correlation function in equilibrium. We show that, in contrast to the second noise (noise of noise), the noise of susceptibility is a direct measure of non-Gaussian fluctuations in the system. We develop a general framework for calculating the noise of susceptibility using the Majorana representation of spin-1/2 operators. We illustrate our approach by a simple example of non-interacting spins coupled to a dissipative (Ohmic) bath.

arXiv comment10 pages, 4 figures

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Cited by in corpus (13)

• Interacting two-level defects as sources of fluctuating high-frequency noise in superconducting circuits
• The Theory of Spin Noise Spectroscopy: A Review
• Dephasing-assisted Gain and Loss in Mesoscopic Quantum Systems
• Keldysh meets Lindblad: Correlated Gain and Loss in Higher-Order Perturbation Theory
• Majorana representation for dissipative spin systems
• Higher order spin noise spectroscopy of atomic spins in fluctuating external fields
• Broadband spectroscopy of thermodynamic magnetization fluctuations through a ferromagnetic spin-reorientation transition
• Far from equilibrium field theory for strongly coupled light and matter: dynamics of frustrated multi-mode cavity QED
• Bilinear Majorana representations for spin operators with spin magnitudes $S>1/2$
• Optical Resonance Shift Spin Noise Spectroscopy
• Second spectrum of charge carrier density fluctuations in graphene due to trapping/detrapping processes
• Prethermalization of light and matter in cavity-coupled Rydberg arrays
• Distortion of a reduced equilibrium density matrix: influence on quantum emulation