arXiv subjects

Yu-Han Ma

Publications and source records attributed to Yu-Han Ma.

40 records · Page 3Linked to original sources

arXiv2018

Dark information of black hole radiation raised by dark energy

The "lost" information of black hole through the Hawking radiation was discovered being stored in the correlation among the non-thermally radiated particles [Phys. Rev. Lett 85, 5042 (2000), Phys. Lett. B 675, 1 (2009)]. This correlation information, which has not yet been proved locally observable in principle, is named by dark information. In this paper, we systematically study the influences of dark energy on black hole radiation, especially on the dark information. Calculating the radiation spectrum in the existence of dark energy by the approach of canonical typicality, which is reconfirmed by the quantum tunneling method, we find that the dark energy will effectively lower the Hawking temperature, and thus makes the black hole has longer life time. It is also discovered that the non-thermal effect of the black hole radiation is enhanced by dark energy so that the dark information of the radiation is increased. Our observation shows that, besides the mechanical effect (e.g., gravitational lensing effect), the dark energy rises the the stored dark information, which could be probed by a non-local coincidence measurement similar to the coincidence counting of the Hanbury-Brown -Twiss experiment in quantum optics.

gr-qc↗

arXiv2017

The heat and work of quantum thermodynamic processes with quantum coherence

Energy is often partitioned into heat and work by two independent paths corresponding to the change in the eigenenergies or the probability distributions of a quantum system. The discrepancies of the heat and work for various quantum thermodynamic processes have not been well characterized in literature. Here we show how the work in quantum machines is differentially related to isochoric, isothermal, and adiabatic processes. We prove that the energy exchanges during the quantum isochoric and isothermal processes are simply depending on the change in the eigenenergies or the probability distributions. However, for a time-dependent system in a non-adiabatic quantum evolution, the transitions between the different quantum states representing the quantum coherence can affect the essential thermodynamic properties, and thus the general definitions of the heat and work should be clarified with respect to the microscopic generic time-dependent system. By integrating the coherence effects in the exactly-solvable dynamics of quantum-spin precession, the internal energy is rigorously transferred as the work in the thermodynamic adiabatic process. The present study demonstrates that quantum adiabatic process is sufficient but not necessary for thermodynamic adiabatic process.

quant-ph↗

arXiv2017

Voltage induced by Coriolis force: a new sensing scheme for rotation velocity

We study the motion of the charged particles between a pair of conductor plates in the non-inertial reference frame. It is found that there exists a stable voltage between the two conductor plates, which is proportional to the rotation velocity of the non-inertial system. This effect is similar to the Hall effect as the result of the Lorenz force. As an application, we propose a rotation velocity measurement scheme based on this Coriolis force -induced effect.

physics.class-ph↗

arXiv2017

Quantum thermodynamic cycle with quantum phase transition

With the Lipkin-Meshkov-Glick (LMG) model as an illustration, we construct a thermodynamic cycle composed of two isothermal processes and two isomagnetic field processes and study the thermodynamic performance of this cycle accompanied by the quantum phase transition (QPT). We find that for a finite particle system working below the critical temperature, the efficiency of the cycle is capable of approaching the Carnot limit when the external magnetic field λ_{1} corresponding to one of the isomagnetic processes reaches the crosspoint of the ground states' energy level, which can become critical point of the QPT in large N limit. Our analysis proves that the system's energy level crossings at low temperature limits can lead to significant efficiency improvement of the quantum heat engine. In the case of the thermodynamics limit, analytical partition function is obtained to study the efficiency of the cycle at high and low temperature limits. At low temperatures, when the magnetic fields of the isothermal processes are located on both sides of the critical point of the QPT, the cycle obtains the maximum efficiency and the Carnot efficiency can be achieved. This observation demonstrate that the QPT of the LMG model below critical temperature is beneficial to the thermodynamic cycle's operation.

quant-ph↗