318 research outputs found
Thermodynamics of acoustic black holes in two dimensions
It is well-known that the thermal Hawking-like radiation can be emitted from
the acoustic horizon, but the thermodynamic-like understanding for acoustic
black holes was rarely made. In this paper, we will show that the kinematic
connection can lead to the dynamic connection at the horizon between the fluid
and gravitational models in two dimension, which implies that there exists the
thermodynamic-like description for acoustic black holes. Then, we discuss the
first law of thermodynamics for the acoustic black hole via an intriguing
connection between the gravitational-like dynamics of the acoustic horizon and
thermodynamics. We obtain a universal form for the entropy of acoustic black
holes, which has an interpretation similar to the entropic gravity. We also
discuss the specific heat, and find that the derivative of the velocity of
background fluid can be regarded as a novel acoustic analogue of the
two-dimensional dilaton potential, which interprets why the two-dimensional
fluid dynamics can be connected to the gravitational dynamics but difficult for
four-dimensional case. In particular, when a constraint is added for the fluid,
the analogue of a Schwarzschild black hole can be realized
Infinite Volume of Noncommutative Black Hole Wrapped by Finite Surface
The volume of a black hole under noncommutative spacetime background is found
to be infinite, in contradiction with the surface area of a black hole, or its
Bekenstein-Hawking (BH) entropy, which is well-known to be finite. Our result
rules out the possibility of interpreting the entropy of a black hole by
counting the number of modes wrapped inside its surface if the final
evaporation stage can be properly treated. It implies the statistical
interpretation for the BH entropy can be independent of the volume, provided
spacetime is noncommutative. The effect of radiation back reaction is found to
be small and doesn't influence the above conclusion
A protocol of potential advantage in the low frequency range to gravitational wave detection with space based optical atomic clocks
A recent proposal describes space based gravitational wave (GW) detection
with optical lattice atomic clocks [Kolkowitz et. al., Phys. Rev. D 94, 124043
(2016)] [1]. Based on their setup, we propose a new measurement method for
gravitational wave detection in low frequency with optical lattice atomic
clocks. In our method, n successive Doppler signals are collected and the
summation for all these signals is made to improve the sensitivity of the
low-frequency GW detection. In particular, the improvement is adjustable by the
number of Doppler signals, which is equivalent to that the length between two
atomic clocks is increased. Thus, the same sensitivity can be reached but with
shorter distance, even though the acceleration noises lead to failing to
achieve the anticipated improvement below the inflection point of frequency
which is determined by the quantum projection noise. Our result is timely for
the ongoing development of space-born observatories aimed at studying physical
and astrophysical effects associated with low-frequency GW
Transfer of Gravitational Information through a Quantum Channel
Gravitational information is incorporated into an atomic state by correlation
of the internal and external degrees of freedom of the atom, in the present
study of the atomic interferometer. Thus it is difficult to transfer
information by using a standard teleportation scheme. In this paper, we propose
a novel scheme for the transfer of gravitational information through a quantum
channel provided by the entangled atomic state. Significantly, the existence of
a quantum channel suppresses phase noise, improving the sensitivity of the
atomic interferometer. Thus our proposal provides novel readout mechanism for
the interferometer with an improved signal-to-noise ratio
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