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Quantum jump data associated with the article "Solomon equation for qubit and two-level systems" by M. Spiecker et al. acquired and prepared at the Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. The quantum jump data was extracted from the qubit relaxation available at https://doi.org/10.5281/zenodo.7817552 associated with the article "Two-level system hyperpolarization using a quantum Szilard engine" (arXiv:2204.00499). We use the relaxation data from 5ms onwards where the qubit and the TLSs are close to thermal equilibrium. The data is stored in NumPy binary compressed .npz format in the shape (run, polarization time, polarization to excited/ground state, qubit initialization to excited/ground state, repetitions, quantum jump trace). The video shows the quantum jump statistics evolving in time. Each frame in the video corresponds to taking a histogram over all quantum jumps within a quantum jump trace and all repetitions. For additional information please contact: martin.spiecker@kit.edu or ioan.pop@kit.edu.

We present a quantitative bibliometric study of flow battery technology from the first zinc-bromine cells in the 1870’s to megawatt vanadium RFB installations in the 2020’s. We emphasize, that the cost advantage of RFBs in multi-hour charge-discharge cycles is compromised by the inferior energy efficiency of these systems, and that there are limits on the efficiency improvement due to internal cross-over and the cost of power (at low current densities) and due to acceptable pressure drop (at high current densities). Differences between lithium-ion and vanadium redox flow batteries (VRFBs) are discussed from the end-user perspective. We conclude, that the area-specific resistance, cross-over current and durability of contemporaneous VRFBs are appropriate for commercialization in multi-hour stationary energy storage markets, and the most import direction in the VRFB development today is the reduction of stack materials and manufacturing costs. Chromium-iron RFBs should be given a renewed attention, since it seems to be the most promising durable low-energy-cost chemistry.

The randomness of some irreversible quantum phenomena is a central question because irreversible phenomena break quantum coherence and thus yield an irreversible loss of information. The case of quantum jumps observed in the fluorescence of a single two-level atom illuminated by a quasi-resonant laser beam is a worked example where statistical interpretations of quantum mechanics still meet some difficulties because the basic equations are fully deterministic and unitary. In such a problem with two different time scales, the atom makes coherent optical Rabi oscillations between the two states, interrupted by random emissions (quasi-instantaneous) of photons where coherence is lost. To describe this system, we already proposed a novel approach, which is completed here. It amounts to putting a probability on the density matrix of the atom and deducing a general “kinetic Kolmogorov-like” equation for the evolution of the probability. In the simple case considered here, the probability only depends on a single variable θ describing the state of the atom, and p(θ,t) yields the statistical properties of the atom under the joint effects of coherent pumping and random emission of photons. We emphasize that p(θ,t) allows the description of all possible histories of the atom, as in Everett’s many-worlds interpretation of quantum mechanics. This yields solvable equations in the two-level atom case.

We present simulations of the superradiant dynamics of ensembles of atoms in the presence of collective and individual atomic decay processes. We unravel the density matrix with Monte-Carlo wave-functions and identify the quantum jumps in a reduced Dicke state basis, which reflects the permutation symmetry of the identical atoms. While the number of density matrix elements in the Dicke representation increases polynomially with atom number, the quantum jump dynamics populates only a single Dicke state at the time and thus efficient simulations can be carried out for tens of thousands of atoms. The calculated superradiance pulses from initially excited atoms agree quantitatively with recent experimental results with strontium atoms but rapid atom loss in these experiments does not permit steady-state superradiance. By introducing an incident flux of new atoms, the system can maintain a large average atom number, and our theoretical calculations predict lasing with millihertz linewidth despite rapid atom number fluctuations., Comment: 7 pages, 4 figures

We investigate time-dependent spectra of the intermittent resonance fluorescence of a single, laser-driven, three-level atom due to electron shelving. After a quasi-stationary state of the strong transition, a slow decay due to shelving leads to the steady state of the three-level system. The long-term stationary spectrum consists of a coherent peak, an incoherent Mollow-like structure, and a very narrow incoherent peak at the laser frequency. We find that in the ensemble average dynamics the narrow peak emerges during the slow decay regime, after the Mollow spectrum has stabilized, but well before an average dark time has passed. The coherent peak, being a steady state feature, is absent during the time evolution of the spectrum, 5 pages, 4 figures

Exact quasi-classical asymptotic beyondWKB-theory and beyondMaslov canonical operatorto theColombeau solutions of the-dimensional Schrodinger equationis presented. Quantum jumps nature is considered successfully. We pointed out that an explanation ofquantum jumps can be found to result from Colombeausolutions of the Schrödinger equation alone without additional postulates.

We describe a method to create superposition states from a mixed state of a harmonic oscillator. If the initial state is described by a thermal state, then the resulting superposition state will be a ``hot'' superposition state. Such a state can be distinguished from a statistical mixture by its coherence properties. Here we suggest how to demonstrate the coherence of the superposition state by observing interference fringes when the two parts of the wave packet are overlapped. In the case of the mixed superposition state, a partial overlap may not be sufficient to observe the presence of fringes. We introduce therefore the idea of a coherence length for the wave packet and demonstrate its relevance for interferometry of mixed states. We illustrate our ideas with the example of superposition states for the motion of a single trapped ion.

The maximum-likelihood estimation method is considered. It is based on three-level Oehmelt scheme of isolated quantum system and it makes use of the theory of Markov-modulated Poison process (MMPP). This method is applied to the analysis of the photon-counting distribution resulting &om a single molecule fluorescence experiment. It is assumed that the data available for the estimation contain only the number of collected photons per time interval.