We look for classical traces of the Unruh effect in gravity waves. For this purpose, we start considering a white noise state of gravity waves on the surface of a water basin and calculate the two- and four-point functions of the Fourier transform of the surface-height field with respect to accelerated observers. The influence of the basin boundaries and possible deviations from Gaussianity in the white noise state are considered in order to approximate conditions attainable in the laboratory. Eventually, we make the basin infinitely large in order to make contact between our classical results and quantum ones derived in free space. We hope that our results help to strengthen the bridge between the Unruh effect and this classical analog.
Matter fields are supertranslated upon crossing a shock wave, which leads to entanglement of the quantum vacuum between the two regions on either side of the shock wave. We probe this entanglement for a scalar field in a planar shock wave background by computing the Bogoliubov transformation between the inertial and uniformly accelerated observer. The resulting Bogoliubov coefficients are shown to reproduce the standard Unruh effect without dependence on the form factor of the shock wave. In contrast, excited states lead to observables that depend upon the form factor. In the context of nonsph…
We derive the solutions of gravitational waves in the future (F) expanding and the past (P) shrinking Kanser spacetimes as well as in the left (L) and right (R) Rindler wedges in the Regge-Wheeler gauge. The solutions for all metric components are obtained in an analytic form in each region. We identify the master variables, which are equivalent to massless scalar fields, to describe the gravitational degrees of freedom for the odd parity and even parity modes under the transformation in the two-dimensional plane symmetric space. Then, the master variables are quantized, and we develop the qua…
We firstly generalize the massive scalar propagator for planar gravitational waves propagating on Minkowski space obtained recently in Ref. [1]. We then use this propagator to study the response of a freely falling Unruh-DeWitt detector to a gravitational wave background. We find that a freely falling detector completely cancels the effect of the deformation of the invariant distance induced by the gravitational waves, such that the only effect comes from an increased average size of scalar field vacuum fluctuations, the origin of which can be traced back to the change of the surface in which …
Applying the techniques of light-front quantization to quantize a scalar field in a monochromatic gravitational wave background, we manage to investigate the response of the Unruh-DeWitt detector coupled to a scalar field in the presence of a gravitational wave for the two cases moving along a free-falling trajectory and a constant-accelerating trajectory. The transition rate of the Unruh-DeWitt detector, in both cases, is different from the result with no gravitational wave, and the leading-order correction due to the gravitational wave survives the long-wavelength limit that formally takes t…
The Unruh effect is essential to keep the consistency of quantum field theory in inertial and uniformly accelerated frames. Thus, the Unruh effect must be considered as well tested as quantum field theory itself. In spite of it, it would be nice to realize an experiment whose output could be directly interpreted in terms of the Unruh effect. This is not easy because the linear acceleration needed to reach a temperature 1 K is of order $10^{20} {\rm m/s}^2$. We discuss here a conceptually simple experiment reachable under present technology which may accomplish this goal. The inspiration for th…
The Unruh effect is the prediction that an accelerating object perceives its surroundings as a bath of thermal radiation even if it accelerates in vacuum. The Unruh effect is believed to be very difficult to observe in the experiment, since an observer accelerating at g=9.8 m/s2 should see vacuum temperature of only 4x10^-20 K. Here we demonstrate that photons in metamaterial waveguides may behave as massive quasi-particles accelerating at up to 10^24 g, which is about twelve orders of magnitude larger than the surface acceleration near a stellar black hole. These record high accelerations may…
Derived from semi-classical quantum field theory in curved spacetime, Unruh effect was known as a quantum effect. We find that there does exist a classical correspondence of this effect in electrodynamics. The thermal nature of the vacuum in correlation function for the uniformly accelerated detector is coming from the non-linear relationship between the proper time and the propagating length of the electromagnetic wave. Both the Coulomb field of the detector itself and the radiation supporting the detector's uniformly accelerating motion contribute to the non-vanishing vacuum energy. From thi…
We studied the change of the nonlocal correlation of the entanglement in Rindler spacetime by showing that the Unruh effect can be interpreted as a noisy quantum channel having a complete positive and trace preserving map with an operator sum representation. It is shown that the entanglement fidelity is obtained in analytic form from the operator sum representation, which agrees well numerically with the entanglement monotone and the entanglement measure obtained previously. Non-zero entropy exchange between the system Q and the region II of the Rindler wedge indicates the nonlocal correlation…
Thomas Jefferson National Accelerator Facility（托马斯·杰斐逊国家加速器设施）；SLAC National Accelerator Laboratory, Stanford University（斯坦福大学SLAC国家加速器实验室）；Nanjing University（南京大学）；Institute for Nonperturbative Physics, Nanjing University（南京大学非微扰物理研究所）；Old Dominion University（老道明大学）
We analyse the emergence of the Unruh effect within the context of a field Lagrangian theory associated to the Pais-Uhlenbeck fourth order oscillator model. To this end, we introduce a transformation that brings the Hamiltonian bounded from below and is consistent with $\mathcal{PT}$-symmetric quantum mechanics. We find that, as far as we consider different frequencies within the Pais-Uhlenbeck model, a particle together with an antiparticle of different masses are created as may be traced back to the Bogoliubov transformation associated to the interaction between the Unruh-DeWitt detector and…
In the Unruh effect an observer with constant acceleration perceives the quantum vacuum as thermal radiation. The Unruh effect has been believed to be a pure quantum phenomenon, but here we show theoretically how the effect arises from the classical correlation of noise. We demonstrate this idea with a simple experiment on water waves where we see the first indications of a Planck spectrum in the correlation energy.
We show that massive particles created in a relativistically accelerated reference frame, as predicted by the Unruh effect, can only be found in a tiny layer above the event horizon, whose thickness corresponds to a single Compton wavelength. This is beyond the reach of any detector and suggests that the Unruh effect may not ever be directly observed for massive fields. The case of massless particles is also examined, for which qualitatively different behaviour is observed in a low-acceleration regime, suggesting that an observation of the Unruh effect for massless particles is more promising.
Corrections to the Unruh Effect from Robin Boundary Conditions in Punctured Minkowski Spacetime
Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas（坎皮纳斯州立大学格莱巴·瓦塔金物理研究所）；Departamento de Matemática Aplicada, Universidade Estadual de Campinas（坎皮纳斯州立大学应用数学系）；Universidade Estadual de Campinas（坎皮纳斯州立大学）
Using the Fermat's principle in curved space-time with stationary type metric, we have obtained the speed of light as a function of spatial coordinates and hence the corresponding refractive index. The whole region with space dependent gravity is divided into a number of overlapping transparent refracting media with varying refractive index. The refractive index is found to be increasing with the strength of gravitational field. Hence using the laws of refraction, we have explained the gravitational bending of light. Further using the conventional idea of total internal reflection of light whi…
We have computed the number of polarization modes of gravitational waves propagating in the Minkowski background in $f(R)$ gravity. This is three of two from transverse-traceless tensor modes and one from a massive trace mode, which confirms the results found in the literature. There is no massless breathing mode and the massive trace mode corresponds to the Ricci scalar. A newly defined metric tensor in $f(R)$ gravity satisfies the transverse-traceless (TT) condition as well as the TT wave equation.
Horizon effects with surface waves on moving water
在一个线性模型，其中包括表面张力的流体被认为是在一个稳定的水流表面波。由此产生的重力毛细波的经验丰富的地平线上的影响时，逆着流传播。在某些情况下，对于具有单一实验室频率的波，存在三个层位（波的群速度反转的点）。这些效应中的一些在流体力学中以波阻塞的名义是熟悉的，但是其他方面，特别是具有负同向移动频率的波和霍金效应，被忽略了，直到表面波作为模拟重力的例子被研究[Schützhold R和Unruh W G 2002 Phys. Rev. D 66 044019]。本文对重力-毛细波的各种层位效应作了全面的介绍，着重讨论了深水/短波长情况kh>>1，在这种情况下可以得到许多解析结果。的波的热力学系统的状态空间的相似性指出。
We construct a classification of dispersion relations for the electromagnetic waves non-minimally coupled to the space-time curvature, based on the analysis of the susceptibility tensor, which appears in the non-minimal Einstein-Maxwell theory. We classify solutions to the Fresnel equation for the model with a trace-free non-minimal susceptibility tensor according to the Petrov scheme. For all Petrov types we discuss specific features of the dispersion relations and plot the corresponding wave surfaces.
We discuss gravitational waves (GWs) induced by a heavy spectator field that starts to oscillate during inflation. During the oscillation of the spectator field, its effective mass can also oscillate in some potentials. This mass oscillation can resonantly amplify the spectator field fluctuations. We show that these amplified fluctuations can induce large GWs, which could be investigated by future gravitational wave observations. This kind of induced GW can be produced even if the spectator field does not have any interaction with other fields except for gravitational interaction.
Relying only on the standard model of elementary particles and gravity, we study the details of a new source of gravitational waves whose origin is in quantum physics. Namely, it is well known that massless fields in curved backgrounds suffer from the so-called "trace anomaly". This anomaly can be cast in terms of new scalar degrees of freedom which take account of macroscopic effects of quantum matter in gravitational fields. The linearized effective action for these fields describes scalar (as opposed to transverse) gravitational waves, which are absent in Einstein's theory. Since these new …
