1,665 research outputs found
Rare quantum metastable states in the strongly dispersive Jaynes-Cummings oscillator
We present evidence of metastable rare quantum-fluctuation switching for the
driven dissipative Jaynes-Cummings oscillator coupled to a zero-temperature
bath in the strongly dispersive regime. We show that single-atom complex
amplitude bistability is accompanied by the appearance of a low-amplitude
long-lived transient state, hereinafter called `dark state', having a
distribution with quasi-Poissonian statistics both for the coupled qubit and
cavity mode. We find that the dark state is linked to a spontaneous flipping of
the qubit state, detuning the cavity to a low-photon response. The appearance
of the dark state is correlated with the participation of the two metastable
states in the dispersive bistability, as evidenced by the solution of the
Master Equation and single quantum trajectories.Comment: Extensively revised text, 18 revised figures (16 in main and 2 in
appendix), 38(+1) references, appendi
C Wright Mills, power and the power elites ? a reappraisal
This paper revisits and presents a critical appraisal of Mills's analysis of power and the power elite. There are signs of a revival of interest in Mills, but recent commentators have shown little interest in the intellectual, social or political context of his analysis. Setting Mills's thesis in its historical context, we consider an element of his project that has been particularly neglected in recent discussion: Mills's search for possible ways of redistributing power and his attempt to forge an ethico-political stance. Reflecting on recent discussion of contemporary elite formations, we comment on what critics might take from Mills in our own time in relation to the analysis of elites and the politics of critical management studies
Parallel quantum simulation of large systems on small NISQ computers
Tensor networks permit computational and entanglement resources to be concentrated in interesting regions of Hilbert space. Implemented on NISQ machines they allow simulation of quantum systems that are much larger than the computational machine itself. This is achieved by parallelising the quantum simulation. Here, we demonstrate this in the simplest case; an infinite, translationally invariant quantum spin chain. We provide Cirq and Qiskit code that translates infinite, translationally invariant matrix product state (iMPS) algorithms to finite-depth quantum circuit machines, allowing the representation, optimisation and evolution of arbitrary one-dimensional systems. The illustrative simulated output of these codes for achievable circuit sizes is given
Fatigue in celiac disease: A review of the literature
Fatigue is increasingly recognized as a significant problem in patients with chronic inflammatory and autoimmune diseases. In celiac disease, a chronic immune‐mediated disease triggered by dietary gluten, conflicting opinions exist regarding both the size of the problem and the effect of a gluten‐free diet (GFD) on fatigue. We reviewed the existing literature regarding fatigue in celiac disease. We conducted a systematic search in the Embase, Ovid Medline, and Cochrane databases using subject terms from controlled vocabularies. Articles were reviewed based on language, type of article, title, and abstract or full text. Eighteen articles were finally selected for review. Fatigue was significantly greater in patients with celiac disease compared to healthy control subjects. Fatigue prevalence ranged from 8 to 100%. Fatigue severity was assessed in six studies. The fatigue visual analogue scale was the most frequently used fatigue instrument with scores from 57 to 79 prior to starting a GFD and from 39 to 59 in patients on a GFD. Seven studies investigated the effect of a GFD on fatigue, including five studies that reported less fatigue while on the diet and two studies that showed no significant difference. This review concludes that fatigue is a substantial complaint in patients with celiac disease. A GFD seems to reduce fatigue, but existing data are limited.publishedVersio
Rayleigh-B\'{e}nard convection in a homeotropically aligned nematic liquid crystal
We report experimental results for convection near onset in a thin layer of a
homeotropically aligned nematic liquid crystal heated from below as a function
of the temperature difference and the applied vertical magnetic
field and compare them with theoretical calculations. The experiments cover
the field range 8 \alt h \equiv H/ H_{F} \alt 80 ( is the
Fr\'eedericksz field). For less than a codimension-two field the bifurcation is subcritical and oscillatory, with travelling- and
standing-wave transients. Beyond the bifurcation is stationary and
subcritical until a tricritical field is reached, beyond which it
is supercritical. The bifurcation sequence as a function of found in the
experiment confirms the qualitative aspects of the theoretical predictions.
However, the value of is about 10% higher than the predicted value and
the results for are systematically below the theory by about 2% at small
and by as much as 7% near . At , is continuous within
the experimental resolution whereas the theory indicates a 7% discontinuity.
The theoretical tricritical field is somewhat below the
experimental one. The fully developed flow above for is
chaotic. For the subcritical stationary bifurcation also
leads to a chaotic state. The chaotic states persist upon reducing the Rayleigh
number below , i.e. the bifurcation is hysteretic. Above the tricritical
field , we find a bifurcation to a time independent pattern which within
our resolution is non-hysteretic.Comment: 15 pages incl. 23 eps figure
A New Approach toward Transition State Spectroscopy
Chirped-Pulse millimetre-Wave (CPmmW) rotational spectroscopy provides a new
class of information about photolysis transition state(s). Measured intensities
in rotational spectra determine species-isomer-vibrational populations,
provided that rotational populations can be thermalized. The formation and
detection of S0 vinylidene is discussed in the limits of low and high initial
rotational excitation. CPmmW spectra of 193 nm photolysis of Vinyl Cyanide
(Acrylonitrile) contain J=0-1 transitions in more than 20 vibrational levels of
HCN, HNC, but no transitions in vinylidene or highly excited local-bender
vibrational levels of acetylene. Reasons for the non-observation of the
vinylidene co-product of HCN are discussed.Comment: Accepted by Faraday Discussion
Dissipative failure of adiabatic quantum transport as a dynamical phase transition
Entanglement is the central resource in adiabatic quantum transport. Dephasing affects the availability of that resource by biasing trajectories, driving transitions between success and failure. This depletion of entanglement is important for the practical implementation of quantum technologies. We present an alternative perspective on the failure of adiabatic computation by understanding the failure of adiabatic transport as a dynamical phase transition. These ideas are demonstrated in a toy model of adiabatic quantum transport in a two-spin system
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