Questions tagged [unruh-effect]

This tag is for questions regarding to the Unruh effect (also known as the Fulling–Davies–Unruh effect), the hypothetical prediction that an accelerating observer will observe a thermal bath, like blackbody radiation, whereas an inertial observer would observe none. It was described by Stephen Fulling in 1973, Paul Davies in 1975, and William Unruh in 1976.

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Does the Unruh effect assume its conclusion?

Unruh effect says that accelerating observers see the single particle states of inertial frames as thermal baths. But it proves it by defining the particle states in the accelerating observer's frame ...
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Might the tiny Hawking radiation from our cosmic event horizon (CEH) be additive, since my CEH is not your CEH?

Concerning our cosmic event horizon, an interesting question arises from the seemingly innocent statement, "My cosmic event horizon is not your cosmic event horizon." Ie: Since 'you' and 'I'...
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Informal derivation of the Unruh temperature

Imagine a charged particle of mass $m$ at rest in the electromagnetic vacuum. The particle interacts most strongly with zero-point modes that have a wavelength $\lambda_C$ similar to the Compton ...
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Unruh effect origin of particle

I have a little confusion about where from the particle are coming in Unruh effect. Vacuum fluctuation is always there and does not depend on whether the frame/detector is moving or not. Vacuum ...
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Calculation of expectation of number of particle using Bogolubov transformation [closed]

we have two bases connected by Bogoljubov transformations. In the first basis, creation and annihilation operators are ($a,a^\dagger$) and in the second basis ($a',a'^\dagger$). They are connected by \...
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Proof probability distribution of number of particles seen in different basis connected by Bogoljubov transformation is Poissonian

Let we have two bases connected by Bogoljubov transformations. In the first basis, creation and annihilation operators are ($a,a^\dagger$) and in the second basis ($a',a'^\dagger$). They are connected ...
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Significance of non-zero cross energy-momentum tensor in Fulling Davies Unruh effect

In the Fulling Davies Unruh effect We can get the outgoing particle flux from the asymptotic future region $\mathscr{I}^+$ from the mirror trajectory as the following $$ \mathcal{F}=\int_0^\infty \...
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An example of the vacuum emitting photons?

Imagine we have two parallel wires with a potential difference of $V$ volts that form the opposite sides of a square of size $\lambda$. Any virtual electron-positron pairs that form between the wires ...
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Does an electric field cause the vacuum to emit photons?

As I understand it electron-positron pairs pop in and out of the vacuum on a time scale $T$ inversely proportional to the electron mass. Imagine we put a static electric field across the vacuum. ...
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Deriving Hawking temperature "from" Unruh effect and their relation

Let me recall some basic computational facts (the meaning of which I am trying to understand). In flat space, an adapted coordinate $(\tau, \xi)$ associated with an observer with constant proper ...
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Do the null geodesics of photons emitted by Hawking radiation arise from the event horizon?

It is a well-known explanation of Hawking radiation that it originates from the quantum fluctuations near the horizon. Does it mean that one can look at the photons (part of the radiation) and follow ...
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Symmetry restoration in accelerated frames

I am trying to understand the symmetry restoration in accelerated frames. I was reading 1 and 2. Can somebody help me to understand how they got Eq. 7.12 in 1 or Equation just after Eq.3.3 in 2? In ...
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Carroll's derivation of Hawking radiation

In Carroll's Spacetime and Geometry: An Introduction to General Relativity, in his derivation of Hawking radiation Carroll makes the following statement: "as observed over length and timescales ...
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Lowering the Schwinger limit with superconductors while considering the Unruh effect?

Unruh Effect is often left out in calculations regarding the Schwinger limit. I've been looking at different mechanisms for more easily attaining the Schwinger limit. So far, the only thing I have ...
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Rindler decomposition using Euclidean path integral

In section 3.3 of Jerusalem Lectures on Black Holes and Quantum Information (arXiv:1409.1231), Daniel Harlow wants to calculate the following Euclidean path integral $$\langle\phi |\Omega\rangle\...
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How to derive the Unruh effect (or the thermofield double state) from the path integral?

I have been reading about the path integral approach to deriving the thermofield double state for the Minkowski vacuum in terms of the Rindler states: \begin{equation} \left|0_{M}(t=0)\right\rangle=\...
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Questions about the Unruh effect derivation in Wald's QFT in curved spacetime

So I'm currently reading chapter 5 of Wald's book on QFT in curved spacetime and I'm terribly confused with the notation in the last steps of his Unruh effect derivation. Context: In eq. 5.1.26, he ...
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Is the experimental evidence confirming black hole entropy or Unruh radiation?

The question says it all: how does Bekenstein–Hawking entropy or radiation fare when compared with observation? Or maybe just the idea of Unruh radiation?
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In the Unruh effect, where does the energy of the particles come from?

If you accelerate an object with constant acceleration, you will in effect create a black hole in the opposite direction in which you are traveling. This being due to light rays at a certain distance ...
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Does the count of particles depend on the observer?

The Lagrangian and Action, say in QED, is invariant to Lorentz boosts and independent of observers. (It’s possible to convert from a Lagrangian to the Hamiltonian view via a Legendre transform $H=vp-L$...
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Physical significance of number operator in QFT

Does the expectation value of the number operator corresponds to any physical observable or has any significance in classical limit? This is probably a dumb question, but I'm struggling to identify ...
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Why Unruh temperature is the temperature measured by observer with $\xi = 0$?

My coordinate transformation is: \begin{align} t=\frac{1}{a} e^{a \xi} \sinh (a \eta), \quad x=\frac{1}{a} e^{a \xi} \cosh (a \eta). \end{align} The free scalar field is quantized under this ...
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Doubts about the "periodicity trick" to compute temperature

The "periodicity trick" is a mysterious way to compute some sort of temperature associated to a Rindler-like spacetime. Suppose there exist coords $R\in(0,\infty), \eta\in(-\infty,\infty)$ ...
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Unruh radiation "observed" by a particle undergoing Brownian motion

The Unruh effect is a basic result from the theory of quantum fields in curved space-time (a sort of precursor to quantum gravity) which can be thought of as describing how the ground state of ...
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Hawking Temperature for a Given Metric

I want to calculate the Hawking temperature of the metric $$\mathrm ds^{2}=-\left(1-\frac{r^{2}}{l^{2}}\right)\mathrm dt^{2}\ +\frac{\mathrm dr^{2}}{\left(1-\frac{r^{2}}{l^{2}}\right)}+\ r^{2}\mathrm ...
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Davies & Unruh: vacuum temperature is proportional to acceleration. But $T$ is not a vector

Davies and Unruh showed that vacuum temperature is given by acceleration: $$T = \frac{\hbar a}{2 \pi k_\mathrm B c}.$$ But acceleration is a vector, temperature is not. If vacuum temperature produces ...
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What is the physical interpretation of negative Unruh temperature?

Actually the Unruh temperature is vectorial since it is proportional to acceleration but derived for only one space dimension so at least positive and negative. What can negative Unruh temperature ...
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Unruh modes inconsistent notation

The Unruh modes as defined in Sean Carroll's "Spacetime and Geometry" are: \begin{equation} h_k^{(1)} = \frac{1}{\sqrt{2\sinh(\pi \omega/a)}}\big(e^{\pi \omega/2a} g_k^{(1)} + e^{-\pi \omega/...
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Unruh effect vacuum state

In Carroll's Spacetime and Geometry I found the following explanation for why the analytically extended Rindler modes share the same vacuum state as the Minkowski vacuum state: The original positive-...
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Unruh effect derivation

I was going through the derivation of the Unruh effect in chapter 5 of these lecture notes ("Lecture Series on Relativistic Quantum Information" by Prof Ivette Fuentes). On p.26 the author ...
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Can Quantum Field Theory not handle accelerated frames of reference?

Since Quantum Field Theory can't handle gravity, and gravity is mathematically equivalent to acceleration (equivalence principle), does this mean Quantum Field theory can't handle accelerated frames ...
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Does Unruh radiation potentially explain the Paradox of 'apparent non-radiation of charged particles in a gravitational field'?

The Wikipedia entry on 'Paradox of radiation of charged particles in a gravitational field' does not mention Unruh or Hawking radiation, but I don't see why they wouldn't provide a solution.... ...
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Does the Unruh effect need the accelerating observer's Hilbert space to be smaller than the inertial one?

I've encounter two different approaches to the Unruh effect and I feel like they are not consistent with one another. Bogoliubov Transformation In this approach the basic statement is that the vacuum ...
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2 votes
2 answers
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Firewall in Rindler horizon

In arXiv:1409.1231 in section 3.5 above equation (3.34) Daniel Harlow says More precisely if the left and right wedges are completely uncorrelated, as in the state 3.33, then the typical difference ...
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Usage of Rindler coordinates in studying Unruh Effect

When studying the Unruh Effect, Rindler coordinates are being used for the observer with constant acceleration. I am confused as to why Rindler coordinates are used as I do not see the motivation for ...
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1 vote
1 answer
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How can Unruh radiation ever be real?

It is speculated that Unruh radiation exists for accelerating observers in flat spacetime. A thermometer in the frame will point at a higher value than for someone in a stationary frame. In the ...
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3 votes
5 answers
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Flux and radiation pressure from Unruh radiation?

A collection of accepted answers on Physics Exchange paint a seemingly inconsistent picture of Unruh radiation and it's isotropy. One of the most sophisticated answers, from Lubosz Motl, to the ...
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Unruh temperature appears to depend on reference frame, how is this resolved?

I am wondering about observer-(in)dependence of Unruh temperature. Specifically, consider two observers, A and B, initially at rest in the same position. Then, at some point, A starts uniformly ...
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How do you show that the Unruh Temperature between two inertial observers is zero?

As part of my undergraduate thesis, I'm trying to show that using massless scalar field, the Unruh effect between two inertial observers is zero. I'm using this book: "Introduction to Quantum ...
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7 votes
3 answers
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Interpretation of the nonuniqueness of vacuum of QFT in flat spacetime for a given inertial observer; No Lorentz transformation; No accelerated motion

Consider an inertial observer in flat spacetime with a choice of coordinates $(t,{\vec x})$. This observer can expand a quantum field $\hat{\phi}$ in more than one complete set of orthonormal modes. ...
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What is the interpretation of non-uniqueness of field expansion in flat spacetime?

Scalar field expansion in terms of plane wave modes is given by $$\phi(x)=\int\frac{d^3{\vec p}}{\sqrt{(2\pi)^{3}2\omega_{\vec p}}}\left(a_{\vec p}e^{-ip\cdot x}+a_p^\dagger e^{+ip\cdot x}\right)$$ ...
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Unruh effect on rotating galaxies?

According to the Unruh effect, an accelerating observer will experience a thermal bath. This is equivalent to Hawking radiation. If we applied this to a spinning galaxy, I wonder if this thermal bath ...
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Can the inertial observer "see" the Unruh accelerated observer's vacuum?

The unruh process is asymmetric. The inertial observer is in his vacuum V0 and the accelerated observer measures $\langle V_0|N|V_0 \rangle$ and sees particles. He is not in his vacuum environment. I ...
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For Hawking radiation, is the scalar field $\phi$ assumed to be in the Unruh vacuum state?

In Hawking's paper "Particle Creation by Black Holes" I'm not really able to pick apart what vacuum state Hawking is assuming the field $\phi$ to be in. The paper "Hawking radiation as ...
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2 answers
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Isn't Unruh effect against the equivalence principle?

Doesn't the Unruh effect violate EP? Since the temperature of an absolutely accelerating reference frame would be different from an inertial one according to this effect, then one finds a criterion to ...
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Unruh particles

When we accelerate, an event horizon forms behind us resulting in Unruh radiation. In this kind of scenario, the existence of the radiation particles themselves is observer dependent. My question is: ...
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3 votes
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Unruh effect: should Minkowski vacuum transform according to different observers?

It's known that the Minkowski vacuum is observed as a thermal bath for Rindler observers, in paticular: $\langle0_{M}|N_{M}|0_{M}\rangle=0 \space\space\space\space\space\space\space $ (1) $\...
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How to relate the coordinates of a lab-frame observer and an uniformly accelerating observer?

If there is lab-frame observer with coordinates $(t,x)$ and a uniformly acceletaing observer in $1+1$ dimensional flat Minkowski spacetime with coordinates $(t',x')$, can we analytically relate $(t',...
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2 votes
2 answers
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Is the Unruh effect a special relativistic effect or a general relativistic effect?

If an observer moves in an accelerated frame in flat spacetime, the vacuum looks like a thermal distribution of particles to that observer. This is the Unruh effect. Is it a special relativistic (SR) ...
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Why a mode on Minkowsky SpaceTime becomes two modes on Rindler Spacetime

----I am a student on Quantum Computing--- For the whole undertanding of "Tetrapartite entanglement measures of GHZ state with uniform acceleration" by Qiang Dong. https://doi.org/10.1088/...
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