arXiv subjects

Wei-Bin Yan

Publications and source records attributed to Wei-Bin Yan.

12 recordsLinked to original sources

arXiv2026

Nonreciprocal Quantum Mpemba Effect

We demonstrate a nonreciprocal quantum Mpemba effect. Consider a broad class of open quantum systems, each coupled to two isomorphic reservoirs through symmetric ports. Interchanging the parameters of the two reservoirs -- a discrete operation we call the swap -- turns the quantum Mpemba effect on or off without changing the initial states. The swap modifies the Liouvillian, yet a structural symmetry pins the eigenvalues while rotating only the eigenvectors. The nonreciprocity therefore leaves no trace in the spectrum and is carried entirely by the eigenvectors. Concretely, the swap alters the far state's projection onto the slowest mode, switching whether it bypasses the slowest relaxation channel. At a Liouvillian exceptional point, the far state's relaxation switches from bypassing the slowest mode to avoiding the critical slowing, with the on--off contrast intact. There the spectrum-independent mechanism takes its purest form.

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arXiv2024

Qubit coupled with an effective negative-absolute-temperature bath in off-resonant collision model

Quantum collision model provides a promising tool for investigating system-bath dynamics. Most of the studies on quantum collision models work in the resonant regime. In quantum dynamics, the off-resonant interaction often brings in exciting ffects. It is thereby attractive to investigate quantum collision models in the off-resonant regime. On the other hand, a bath with a negative absolute temperature is anticipated to be instrumental in developing thermal devices. The design of an effective bath with negative absolute temperature coupled to a qubit is significant for developing such thermal devices. We establish an effective negative-absolute-temperature bath coupled to a qubit with a quantum collision model in a far-off-resonant regime. We conduct a detailed and systematic investigation on the off-resonant collision model. There is an additional constraint on the collision duration resulting from the far-off resonant collision. The dynamics of the collision model in the far-off-resonant regime are different from the one beyond the far-off-resonant regime. Numerical simulations confirm the validity of the proposed approach.

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arXiv2024

Evidence of genuine quantum effects in nonequilibrium entropy production

Entropy production is a fundamental concept that plays a crucial role in the second law of thermodynamics and the measure of irreversibility. It imposes rigorous constraints on the kinds of transformations allowed in thermodynamic processes. Using an optical setup, here we experimentally demonstrate the division of entropy production of an open quantum system into a population-related component and a coherence-related component, validating previous theoretical predictions. The coherence-related component represents a genuine quantum contribution with no classical counterpart. By adjusting bath temperatures and initial coherences of the system, we first derive the total entropy production due to both populations and coherences, then remove all the coherences of the system to solely obtain the population-related contribution. The difference between these two results permits to isolate the coherence-related term. Based on this division, our experiment ultimately proves that irreversibility at the quantum level can be reduced through properly harnessing the two contributions to entropy production.

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arXiv2023

Temperature-related single-photon transport in waveguide QED

We propose a scheme to realize the single-photon transport affected by the temperature. The scheme is composed by a waveguide-atom interacting structure linked to a thermal bath. The single-photon reflection coefficient can be tuned by adjusting the temperature of the thermal bath. This provides a thermal control of the single-photon transport. Moreover, the temperature of the thermal bath can be estimated by measuring the single-photon transport. It is feasible that the estimation on the temperature is sensitive to slight changes of low temperature. This implies an avenue for implementing the optical thermometer with the ability to accurately measure the sample temperature in the low-temperature region.

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arXiv2022

All-optical control of thermal conduction in waveguide QED

We investigate the heat conduction between two one-dimension waveguides intermediated by a Laser-driving atom. The Laser provides the optical control on the heat conduction. The tunable asymmetric conduction of the heat against the temperature gradient is realized. Assisted by the modulated Laser, the heat conduction from either waveguide to the other waveguide can be suppressed. Meanwhile, the conduction towards the direction opposite to the suppressed one is gained. The heat currents can be significantly amplified by the energy flow of the Laser. Moveover, the scheme can act like a heat engine.

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arXiv2022

Supervised Learning by Chiral-Network-Based Photonic Quantum Computing

Benefiting from the excellent control of single photons realized by the emitter-photon-chiral couplings, we propose a novel potential photonic-quantum-computation scheme to perform the supervised learning tasks. The gates for photonic quantum computation are realized by properly designed atom-photon-chiral couplings. The quantum algorithm of supervised learning, composed by integrating the realized gates, is implemented by the tunable gate parameters. The learning ability is demonstrated by numerically simulating the performance of regression and classification tasks.

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arXiv2018

Tunable single-photon diode by chiral quantum physics

We investigate the single photon scattering by an emitter chirally coupled to a one-dimensional waveguide. The single-photon transport property is essentially different from the symmetrical coupling case. The single photons propagating towards the emitter in opposite directions show different transmission behaviors, which is a manifestation of the single-photon diode. In the ideal chiral coupling case, the transmission probability of the single photon transport in one direction is zero by critical coupling, while in the opposite direction it is unity. The diode works well only when the single-photon frequency meets certain conditions. For a two-level emitter, the diode works well when the single photon is nearly resonant to the emitter. For a $Λ$-type three-level emitter, when the single-photon frequency is greatly altered, we can adjust the parameters of the external laser to ensure the diode works well. The latter provides a manner to realize a single-photon switch, in which the single-photon transmission probability can reach zero or unity although the emitter's decay is considered.

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arXiv2014

All-optical routing of single photons with multiple input and output ports by interferences

We propose a waveguide-cavity coupled system to achieve the routing of photons by the phases of other photons. Our router has four input ports and four output ports. The transport of the coherent-state photons injected through any input port can be controlled by the phases of the coherent-state photons injected through other input ports. This control can be achieved when the mean numbers of the routed and control photons are small enough and require no additional control fields. Therefore, the all-optical routing of photons can be achieved at the single-photon level.

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arXiv2014

Control of single-photon transport in a one-dimensional waveguide by another single photon

We study the controllable single-photon transport in a one-dimensional (1D) waveguide with nonlinear dispersion relation coupled to a three-level emitter in cascade configuration. An extra cavity field was introduced to drive one of the level transitions of the emitter. In the resonance case, when the extra cavity does not contain photons, the input single photon will be reflected, and when the cavity contains one photon, the full transmission of the input single photon can be obtained. In the off-resonance case, the single-photon transport can also be controlled by the parameters of the cavity. Therefore, we have shown that the single-photon transport can be controlled by an extra cavity field.

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arXiv2013

Single-photon quantum router with multiple output ports

We study the multi-channel quantum routing of the single photons in a waveguide-emitter system. The channels are composed by the waveguides and are connected by intermediate two-level emitters. By adjusting the intermediate emitters, the output channels of the input single photons can be controlled. This is demonstrated for the cases of one output channel, two output channels and the generic N output channels. The results show that the multi-channel quantum routing of single photons can be well achieved in present system. This sheds light on the experimental realization of quantum routing of single photons.

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arXiv2013

Tunable single-photon frequency conversion in a Sagnac interferometer

We study the single-photon frequency conversion of a five-level emitter coupled to a Sagnac interferometer. We show that the unity conversion efficiency can be achieved either in resonance or off-resonance case under the ideal condition. In particular, the frequency of the output photon can be controlled by the frequencies and Rabi frequencies of the external driving fields.

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arXiv2013

Single-photon coherent transparency in a coupled atoms-waveguide system

We investigate the single-photon propagation in the one-dimensional waveguide coupled to $N$ two-level atoms. For a waveguide coupled to $N$ distant atoms, the transparency can be induced by coherent interaction at resonance for an $even$ $number$ of $N$, while for an $odd$ $number$ of $N$, the photon can be fully reflected. We then can switch the photon transport by controlling the atomic number. For a waveguide coupled to a small atomic ensemble of $N$ atoms in the same position, the transparency disappears, and the photonic transport property displays a jump behavior near the resonance point.

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