A method is proposed for obtaining the spectrum noise that causes phase decoherence of a qubit directly from experimentally available data. The based on simple relationship between and coherence time in presence π pulse sequence. found to hold every system interacting with classical-noise, bosonic, spin baths.

By introducing a temporal change timescale $\tau_{\text{A}}(t)$ for the time-dependent system Hamiltonian, general formulation of Markovian quantum master equation is given to go well beyond adiabatic regime. In appropriate situations, framework justified even if faster than decay bath correlation function. An application dissipative Landau-Zener model demonstrates this result. The findings are applicable wide range fields, providing basis control

For an open quantum system, we investigate the pumped current induced by a slow modulation of control parameters on basis master equation and full counting statistics. We find that average cumulant generating function quantity are characterized geometrical Berry-phase-like quantities in parameter space, which is associated with generator equation. From our formulation, can discuss pumping under chemical potentials temperatures reservoirs. demonstrate formulation spinless electrons coupled...

We propose a theoretical model of master equation for cathodoluminescence (CL). The describes simultaneous excitation multiple emitters by an incoming electron and radiative decay individual emitters. investigate the normalized second-order correlation function, $g^{(2)}(\tau)$, this model. derive exact formula zero-time delay correlation, $g^{(2)}(0)$, show that successfully giant bunching (superbunching) in CL. also approximate form which is valid small rate. Furthermore, we discuss state...

Abstract Electron microscopy based on high-energy electrons allows nanoscopic analytical imaging taking advantage of secondarily generated particles. Especially for cathodoluminescence, the correlation between primary incident and emitted photons includes information entire interaction process. However, electron-photon time tracking relaxation dynamics luminescent materials has so far not been achieved. In this work, we propose time-correlated electron photon counting microscopy, where...

We derive general properties, which hold for both quantum and classical systems, of response functions nonequilibrium steady states. clarify differences from those equilibrium In particular, sum rules asymptotic behaviors are derived, their implications discussed. Since almost no assumptions made, our results applicable to diverse physical systems. also demonstrate by a molecular dynamics simulation many-body interacting system.

We propose a realistic model for electric conduction, and study transport phenomena by molecular dynamics simulation. observe that the system reaches nonequilibrium steady state in presence of an external field. The electrical conductivity is almost independent impurity distribution size, there no long-time tail. fluctuation–dissipation theorem Kramers–Kronig relation hold at all frequencies. These results show this has normal properties.

We develop a method of calculating the nonequilibrium steady state (NESS) an open quantum system that is weakly coupled to reservoirs in different equilibrium states. describe using Redfield-type master equation (QME). decompose Redfield QME into Lindblad-type and remaining part $\mathcal{R}$. Regarding Lindblad as unperturbed solution, we perform perturbative calculation with respect $\mathcal{R}$ obtain NESS QME. The thus determined exact up first order system-reservoir coupling strength...

Nonequilibrium steady states are investigated in a coupled cavity QED array system which is pumped by thermal bath and dissipated through loss. In the coherent (non-zero photon amplitude) phase, plateau regions appear, where become unchanged against variation of chemical potential bath. The loss plays crucial role for plateaus: plateaus appear only if exists, leakage current, induced loss, essential to mechanism plateaus.

We derive general properties of the linear-response functions nonequilibrium steady states in Langevin systems. These correspond to extension results which were recently found Hamiltonian systems [A. Shimizu and T. Yuge, J. Phys. Soc. Jpn. 79, 013002 (2010)]. discuss one properties, sum rule for response function, particular detail. show that function velocity holds underdamped case, whereas it is violated overdamped case. This implies models should be used with great care. also investigate...

For many-electron systems, we consider a nonequilibrium state (NES) that is driven by pump field(s), which either an optical field or longitudinal electric field. the differential conductivity describing response of NES to probe field, derive exact sum rules and asymptotic behaviors, open wide possibilities for experiments. In deriving these results, have also derived universal properties general functions time-dependent NESs systems.

We study the optically pumped nuclear spin polarization in a single GaAs/AlGaAs quantum well Hall system. apply resistive detection via contact hyperfine interaction, which provides high sensitivity and selectivity, to probe small amount of polarized spins well. The properties optical are clearly observed. theoretically discuss dynamics accompanied with doped electrons analyze experimental data. spectra exhibit electron-spin-resolved lowest Landau level interband transitions. find that...

The time-resolved physical spectrum of luminescence is theoretically studied for a standard cavity quantum electrodynamics system. In contrast to the power steady state, correlation functions up present time are crucial construction spectrum, while correlations with future quantities inaccessible because causality, i.e., cannot be measured until comes. We find that this causality plays key role in understanding which Rabi doublet can never seen during first peak oscillation. Furthermore,...

The fluctuation in electric current nonequilibrium steady states is investigated by molecular dynamics simulation of macroscopically uniform conductors. At low frequencies, appropriate decomposition the spectral intensity into thermal and excess fluctuations provides a simple picture behaving as shot noise. This indicates that fluctuation-dissipation relation may be violated universal manner appearance noise for wide range systems with particle or momentum transport.

The long-time behavior of the velocity autocorrelation function in a classical two-dimensional electric conduction system is studied by molecular dynamics simulation. In equilibrium, effect coexistence many-body interactions and random potential investigated. A crossover from positive tail proportional to t-1, negative -t-2 observed as strength increases. nonequilibrium, enhanced whereas appears at earlier times an field

We study nuclear spin polarization in the quantum Hall regime through optically pumped electron lowest Landau level. The is measured as a magnetic field B(N) by means of sensitive resistive detection. find dependence on filling factor nonmonotonic. comprehensive measurements with help circularly polarized photoluminescence indicate participation photoexcited complexes, i.e., exciton and trion (charged exciton), polarization. On basis novel estimation method equilibrium polarization, we...

The long-time behavior of the velocity autocorrelation function (VACF) is investigated by molecular dynamics simulation a two-dimensional system which has both many-body interaction and random potential. With strengthening potential increasing density impurities, crossover VACF observed from positive tail, proportional to t -1 , negative - -2 . latter tail exists even when particles same order as impurities. in nonequilibrium steady state also studied. In linear response regime similar that...

We investigate energy transfer by the radiation from a cavity quantum electrodynamics (QED) system in context of thermodynamics. propose method decomposing it into work and heat within framework master equations. find that correspond respectively to coherent incoherent parts radiation. In derivation method, is crucial dynamics receives cavity.

Cathodoluminescence (CL), the emission of light induced by accelerated free electrons, has been extensively utilized in various applications, such as displays, streak cameras, and high-spatial-resolution analysis optical material, surpassing diffraction limit light. Despite its long history, photon statistics CL have only recently examined, revealing unexpectedly large bunching photons. Here we find that this peculiar contains information intervening excitation processes before emission,...

We compare rigidity of materials in two phases, liquid and solid phases. As a measure the rigidity, we employ one characterizing how firmly material is fixed by low density pinning centers, such as impurities rough surfaces walls, against weak force. Although more rigid than low-frequency force, find that high-frequency force becomes same material. Since this result derived from universal properties response function, it valid for wide classes materials, including quantum classical systems...

We investigate the connection between superpositions of macroscopically distinct states and known examples speedup in adiabatic quantum computation (AQC). To formalize this notion we consider an index p that quantifies a superposition from asymptotic behaviors fluctuations additive observables. determine for five algorithms exhibiting various degrees speedup. The results suggest is appropriate indicator entanglement crucial to strong AQC.

Abstract To identify the decoherence origin, frequency spectra using multiple π-pulses have been extensively studied. However, little has discussed on how to define spectral intensities from multiple-echo decays and incorporate Hahn-echo T 2 in noise spectra. Here, we show that experiments based two theories solve these issues. As proved previous theory, intensity is given as decay long-time limit. Unlike initial process of decays, this definition not only theoretically proven but also...

Excess work is a nondiverging part of the during transition between nonequilibrium steady states (NESSs). It central quantity in steady-state thermodynamics (SST), which candidate for theory. We derive an expression excess quasistatic transitions NESSs by using macroscopic linear response relation NESS. This line integral vector potential space control parameters. show relationship and function NESS, thus obtain SST quantity. also connect formulation to microscopic physics through function,...