We discuss the possible realizations of the model in various platforms, including optomechanical setups, systems of trapped ions, and circuit QED. Effects of spatial overlap of the baths are addressed. The anisotropic two-qubit interaction is the key to the operation of this simple quantum thermal diode, whose resonant operation allows for high-efficiency rectification of large heat currents. The heat flow rectification is explained by four-wave mixing and Raman transitions between dressed states of the interacting qubits and is governed by a global master equation. We find that if the qubits are coupled by a Raman field that induces an anisotropic interaction, heat flow can become nonreciprocal and undergoes rectification even if the baths produce equal dissipation rates of the qubits, and these qubits can be identical, i.e., mutually resonant. We put forward a quantum-optical model for a thermal diode based on heat transfer between two thermal baths through a pair of interacting qubits. The proposed approach may find diverse applications related to precise probing of the temperature of many-body quantum systems in condensed matter and ultracold gases, as well as in different branches of quantum metrology beyond thermometry, for example in precise probing of different Hamiltonian parameters in many-body quantum critical systems. As opposed to the diverging relative error bound at low temperatures in conventional quantum thermometry, periodic modulation of the probe allows for low-temperature thermometry with temperature-independent relative error bound. Dynamical control in the form of periodic modulation of the energy-level spacings of the quantum probe can dramatically increase the maximum accuracy bound of low-temperatures estimation, by maximizing the relevant quantum Fisher information. Here we consider a thermometer modeled by a dynamically-controlled multilevel quantum probe in contact with a bath. High-precision low-temperature thermometry is a challenge for experimental quantum physics and quantum sensing. These results are expected to open alternative avenues towards unraveling diagnostic information by quantitative MRI. By attaining the ultimate precision limit per measurement, the number of measurements and the total acquisition time may be drastically reduced compared to the present state of the art. We show that currently available MRI pulse sequences can be optimized to attain the ultimate precision limits by choosing control parameters that are uniquely determined by the expected size, the diffusion coefficient, and the spin relaxation time T-2. Here we derive from quantum information theory the ultimate precision limits for obtaining such details by MRI probing of water-molecule diffusion. However, the extraction of reliable information on biomarkers based on microstructure details is still a challenge, as the size of features that can be resolved with noninvasive magnetic resonance imaging (MRI) is orders of magnitude larger than the relevant structures. The underlying quantum thermodynamic principles have far-reaching implications for a broad range of quantum technological applications.Ĭharacterization of microstructures in living tissues is one of the keys to diagnosing early stages of pathology and understanding disease mechanisms. The resulting bath polarization is thereby exponentially enhanced. We propose to remove this impediment by modified cooling schemes, incorporating probe-induced disentanglement or, equivalently, alternating non-commuting probe-bath interactions to suppress the buildup of quantum correlations in the bath. Here we focus on the adverse role of quantum correlations (entanglement) in the spin bath that can impede its cooling in many realistic scenarios. In recent years, significant effort has been invested in identifying the far-reaching consequences of quantum modifications to classical thermodynamics for such processes. Polarizing a spin bath, is the key to enhancing the sensitivity of these tools, leading to new analytical capabilities and improved medical diagnostics. A prominent class of processes where thermodynamic constraints are crucial involve polarization of nuclear spin baths that are at the heart of magnetic resonance imaging, nuclear magnetic resonance (NMR), quantum information processing. The occurrence of any physical process is restricted by the constraints imposed by the laws of thermodynamics on the energy and entropy exchange involved.
0 kommentar(er)
