Quantum torque on a non-reciprocal body out of thermal equilibrium and induced by a magnetic field of arbitrary strength
Quantum torque on a non-reciprocal body out of thermal equilibrium and induced by a magnetic field of arbitrary strength
A stationary body that is out of thermal equilibrium with its environment, and for which the electric susceptibility is non-reciprocal, experiences a quantum torque. This arises from the spatially nonsymmetric electrical response of the body to its interaction with the non-equilibrium thermal fluctuations of the electromagnetic field: the non-equilibrium nature of the thermal field fluctuations results in a net energy flow through the body, and the spatially non-symmetric nature of the electrical response of the body to its interaction with these field fluctuations causes that energy flow to be transformed into a rotational motion. We establish an exact, closed-form, analytical expression for this torque in the case that the environment is the vacuum and the material of the body is described by a damped oscillator model, where the non-reciprocal nature of the electric susceptibility is induced by an external magnetic field, as for magneto-optical media. We also generalise this expression to the context in which the body is slowly rotating. By exploring the high-temperature expansion of the torque, we are able to identify the separate contributions from the continuous spectral distribution of the non-reciprocal electric susceptibility, and from the resonance modes. In particular, we find that the torque persists in the limiting case of zero damping parameter, due to the contribution of the resonance modes. We also consider the low-temperature expansion of the torque. This work extends our previous consideration of this model to an external magnetic field of arbitrary strength, thereby including non-linear magnetic field effects.
Kennedy, Gerard
47b61664-2d2d-45fa-a73a-5af7a7c740cd
Kennedy, Gerard
47b61664-2d2d-45fa-a73a-5af7a7c740cd
Kennedy, Gerard
(2023)
Quantum torque on a non-reciprocal body out of thermal equilibrium and induced by a magnetic field of arbitrary strength.
The European Physical Journal Special Topics.
(In Press)
Abstract
A stationary body that is out of thermal equilibrium with its environment, and for which the electric susceptibility is non-reciprocal, experiences a quantum torque. This arises from the spatially nonsymmetric electrical response of the body to its interaction with the non-equilibrium thermal fluctuations of the electromagnetic field: the non-equilibrium nature of the thermal field fluctuations results in a net energy flow through the body, and the spatially non-symmetric nature of the electrical response of the body to its interaction with these field fluctuations causes that energy flow to be transformed into a rotational motion. We establish an exact, closed-form, analytical expression for this torque in the case that the environment is the vacuum and the material of the body is described by a damped oscillator model, where the non-reciprocal nature of the electric susceptibility is induced by an external magnetic field, as for magneto-optical media. We also generalise this expression to the context in which the body is slowly rotating. By exploring the high-temperature expansion of the torque, we are able to identify the separate contributions from the continuous spectral distribution of the non-reciprocal electric susceptibility, and from the resonance modes. In particular, we find that the torque persists in the limiting case of zero damping parameter, due to the contribution of the resonance modes. We also consider the low-temperature expansion of the torque. This work extends our previous consideration of this model to an external magnetic field of arbitrary strength, thereby including non-linear magnetic field effects.
Text
torque
- Accepted Manuscript
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Accepted/In Press date: 2 December 2023
Identifiers
Local EPrints ID: 485775
URI: http://eprints.soton.ac.uk/id/eprint/485775
ISSN: 1951-6355
PURE UUID: c9db25bb-8ebf-412f-8f44-579587499175
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Date deposited: 18 Dec 2023 20:40
Last modified: 18 Mar 2024 02:59
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