Fluctuation and Dissipation at a Quantum Critical Point

Tong, David; Wong, K. W.

doi:10.1103/physrevlett.110.061602

Cited by 37 publications

(99 citation statements)

References 46 publications

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“…Using the method of holography, as in [33,40], the classical on-shell gravity action of the string moving in the Lifshitz background can be identified as the influence functional for a particle in strongly coupled field theory. We start from considering the finite-temperature nonequilibrium correlators and the zero temperature limit will be taken later.…”

Section: A Influence Functional In Field Theorymentioning

confidence: 99%

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Subvacuum effects in quantum critical theories from a holographic approach

Yeh

Lee²

2016

Phys. Rev. D

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The subvacuum phenomena, induced by the squeezed vacuum of the strongly coupled quantum critical fields with a dynamical scaling z, are explored by a probe particle. The holographic description corresponds to a string moving in 4+1-dimensional Lifshitz geometry with gravitational wave perturbations. The dynamics of the particle can be realized from the motion of the endpoint of the string at the boundary. We then examine the particle's velocity dispersion, influenced by the squeezed vacuum states of the strongly coupled quantum critical fields. With appropriate choices of squeezing parameters, the velocity dispersion is found smaller than the value caused by the normal vacuum fluctuations of the fields. This leads to the subvacuum effect. We find that the large coupling constant of the quantum fields tends to counteract the effect in reduction of velocity dispersion, though this phenomenon is in principle observable. The effect of the squeezed vacuum on the decoherence dynamics of a quantum particle is also investigated. Coherence loss can be shown less severe in certain squeezed vacuums than in normal vacuum. This recovery of coherence is understood as recoherence, another manifestation of the subvacuum phenomena. We make some estimates of the degree of recoherence and find that, on contrary to the velocity dispersion case, the recoherence effect is enhanced by the large coupling constant. Finally we compare the findings in our earlier works when the particle is influenced by a weakly coupled relativistic field with the dynamical scaling z = 1.

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Section: A Influence Functional In Field Theorymentioning

confidence: 99%

“…is connected with the fluctuation-dissipation relation in [33]. In the case of the vacuum state of an environment field, the Fourier transform of the Langevin equation (49) is expressed as…”

Section: Before Proceeding Further It Is Of Interest To See How the mentioning

confidence: 99%

Subvacuum effects in quantum critical theories from a holographic approach

Yeh

Lee²

2016

Phys. Rev. D

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“…The availability of transiently aligned molecular samples has particularly advanced strong-field and attosecond spectroscopies, providing new insights into the electronic structure of molecules and its temporal evolution [3][4][5][6][7]. High-harmonic spectroscopy (HHS) provides a new access to the rich structures of photoionization continua, such as Cooper minima [8][9][10][11] and shape resonances [11][12][13]. The investigation of the inherent structural and dynamical anisotropies of polar molecules has however been prevented by the difficulty of orienting molecules.…”

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confidence: 99%

Two-Pulse Field-Free Orientation Reveals Anisotropy of Molecular Shape Resonance

2014

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We report the observation of macroscopic field-free orientation, i.e. more than 73 % of CO molecules pointing in the same direction. This is achieved through an all-optical scheme operating at high particle densities (> 10 17 cm −3 ) that combines a one-color (ω) and a two-color (ω + 2ω) non-resonant femtosecond laser pulses. We show that the achieved orientation solely relies on the hyperpolarizability interaction as opposed to an ionization-depletion mechanism thus opening a wide range of applications. The achieved strong orientation enables us to reveal the molecularframe anisotropies of the photorecombination amplitudes and phases caused by a shape resonance. The resonance appears as a local maximum in the even-harmonic emission around 28 eV. In contrast, the odd-harmonic emission is suppressed in this spectral region through the combined effects of an asymmetric photorecombination phase and a sub-cycle Stark effect, generic for polar molecules, that we experimentally identify.Techniques for fixing molecules in space are invaluable tools for a broad range of experiments in ultrafast science [1,2]. The availability of transiently aligned molecular samples has particularly advanced strong-field and attosecond spectroscopies, providing new insights into the electronic structure of molecules and its temporal evolution [3][4][5][6][7]. High-harmonic spectroscopy (HHS) provides a new access to the rich structures of photoionization continua, such as Cooper minima [8][9][10][11] and shape resonances [11][12][13]. The investigation of the inherent structural and dynamical anisotropies of polar molecules has however been prevented by the difficulty of orienting molecules. Interesting phenomena tied to polar molecules include the predicted recombination-site dependence of structural minima [14,15] and attosecond charge migration [16][17][18] triggered by strong-field ionization. Here, we demonstrate a protocol for molecular orientation which achieves macroscopic field-free orientation and exploit this progress to probe the anisotropy of photorecombination dipole moments at a molecular shape resonance.Successful approaches to laser-induced molecular orientation include the combination of an electrostatic field with a rapidly turned-off laser field [19], alignment in combination with quantum-state selection and a weak dc-field [20][21][22][23], adiabatic [24] and impulsive two-color orientation [25][26][27]. All of these techniques are subject to substantial limitations: The presence of electric fields may alter the electronic structure of the molecule, its photo-induced dynamics or the subsequent probing process. The low particle densities available after quantumstate selection make the application of such techniques to high-harmonic and attosecond spectroscopies challenging to impossible. The two-color scheme [22,25], recently applied to HHS [26,27], relies on an ionization-depletion mechanism [28] and thus ties the achievable degree of orientation to the ionization fraction of the sample. This fact does not only limi...

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“…2. However, we can employ the low frequency approximation by means of the matching technique [17,[20][21][22]. To find the solutions in this way, we consider three regimes:…”

Section: String Dynamics In Hairy Black Holes and The Response Functionmentioning

confidence: 99%

“…For different theories of gravity one can make an association with various plasmas in the boundary. In this paper we follow different works [16][17][18][19][20][21][22] to investigate the Brownian motion of a particle in a two dimensional plasma of which the gravity dual is described by a three dimensional hairy metric background [23][24][25][26][27][28][29][30][31]. We obtain the solutions to the equation of motion of uncharged hairy black holes by using a matching technique in the low frequency limit.…”

Section: Introductionmentioning

confidence: 99%

Holographic Brownian motion in $$2+1$$ 2 + 1 dimensional hairy black holes

2014

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In this paper, we investigate the dynamics of a heavy quark for plasmas corresponding to three dimensional hairy black holes. We utilize the AdS/CFT correspondence to study the holographic Brownian motion of this particle with different kinds of hairy black holes. For an uncharged black hole in the low frequency limit we derive analytic expressions for the correlation functions and the response functions and verify that the fluctuation-dissipation theorem holds in the presence of a scalar field against a metric background. In the case of a charged black hole, we think that the results are similar to that derived for an uncharged black hole.

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Fluctuation and Dissipation at a Quantum Critical Point

Cited by 37 publications

References 46 publications

Subvacuum effects in quantum critical theories from a holographic approach

Subvacuum effects in quantum critical theories from a holographic approach

Two-Pulse Field-Free Orientation Reveals Anisotropy of Molecular Shape Resonance

Holographic Brownian motion in $$2+1$$ 2 + 1 dimensional hairy black holes

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