- 标题
- 摘要
- 关键词
- 实验方案
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Integral Characteristics of Wave Packets in the Problem of the Evolution of A Wave Function on A One-Dimensional Lattice
摘要： We consider the quantum dynamics of charge transfer on a lattice in the tight-binding approximation and analytically calculate the integral characteristics of the wave packet propagating along the lattice. We focus on calculating the mean and root-mean-square displacements. We also obtain expressions for higher-order moments as series for squares of Bessel functions, which might be independently interesting.
关键词： moments of distribution function,quantum dynamics,tight-binding approximation
更新于2025-09-23 15:22:29
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Dynamic quantum state holography
摘要： We present a pulse-shaper-based holographic technique for the time-resolved and phase-sensitive observation of ultrafast quantum dynamics. The technique combines bichromatic white light polarization pulse shaping with the tomographic reconstruction of photoelectron wave packets. The physical scheme is based on the interference of a probe wave packet from N + 1 resonance-enhanced multiphoton ionization via the target states and a reference wave packet from M + 1 multiphoton ionization of the ground state. To create the wave packets, we employ carrier-envelope phase stable bichromatic (Mω:Nω) pump-probe pulse sequences. The scheme is demonstrated on femtosecond Rydberg wave-packet dynamics in potassium atoms using corotating circularly polarized (2ω:3ω) pulse sequences. The interference of continuum states with different angular momenta yields a crescent-shaped photoelectron wave packet rotating in the laser polarization plane due to the interplay of the optical phase and the accumulated quantum phase. Carrier-envelope phase control of the rotation provides access to the photoelectron asymmetry, enabling background-free detection of the crescent’s angular motion which maps the bound-electron dynamics.
关键词： photoelectron wave packets,ultrafast quantum dynamics,Rydberg wave-packet dynamics,dynamic quantum state holography,bichromatic white light polarization pulse shaping
更新于2025-09-23 15:19:57
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Evaluation of the quantum time-correlation functions employing the Hamilton–Jacobi dynamics framework
摘要： The quantum Hamilton–Jacobi equation (QHJE) is formally equivalent to the time-dependent Schr?dinger equation, and the solutions to the QHJE can be easily interpreted in terms of trajectories providing a link between classical and quantum mechanics. The trajectory-based approaches to quantum molecular dynamics are, generally, appealing because they circumvent exponential scaling associated with exact quantum methods with the system size, and because, unlike classical molecular dynamics, such methods incorporate dominant quantum effects due to delocalization of wavefunctions describing the nuclei. We explore the utility of the QHJE framework for calculations of the time-correlation functions (TCFs) involving quantum evolution defined by the Boltzmann density operator and by the Hamiltonian time-evolution operator. The implementation is based on solutions to the imaginary-time counterpart to the QHJE, which yield approximations to the ground state wavefunction. The resulting nodeless wavefunction is used to generate a basis in coordinate space, which is efficient for evaluation of the low-lying excited states and of the quantum TCFs, including the Kubo-transformed TCFs, at low temperature. The QHJE/basis approach is illustrated on several model systems in and out of thermal equilibrium, i.e., the H2 dimer and bound anharmonic potentials. If a system exhibits large amplitude motion, e.g., in case of the nonequilibrium dynamics, then the real-time trajectory propagation provides an alternative to the basis representation, as demonstrated on a model describing the inversion mode of the ammonia molecule and ion.
关键词： Trajectory dynamics,Time-correlation functions,Excited states,Quantum dynamics
更新于2025-09-23 15:19:57
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Quantum stabilization of microcavity excitation in a coupled microcavitya??half-cavity system
摘要： We analyze the quantum dynamics of a two-level emitter in a resonant microcavity with optical feedback provided by a distant mirror (i.e., a half cavity) with a focus on stabilizing the emitter-microcavity subsystem. Our treatment is fully carried out in the framework of cavity quantum electrodynamics. Specifically, we focus on the dynamics of a perturbed subradiant state of the emitter-microcavity subsystem to ascertain its stability (existence of time oscillatory solutions around the candidate state) or lack thereof. In particular, we find conditions under which multiple feedback modes of the half cavity contribute to the stability, showing certain analogies with the Lang-Kobayashi equations, which describe a laser diode subject to classical optical feedback.
关键词： optical feedback,microcavity,Lang-Kobayashi equations,quantum dynamics,two-level emitter,cavity quantum electrodynamics,stability,subradiant state
更新于2025-09-19 17:13:59
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Entanglement via entangled-boundary-condition trajectories: Long-time accuracy
摘要： Entanglement is considered as a purely quantum effect. The present paper, however, joins many other works that pursue the idea of describing it using classical quantities. In particular, we are interested in the entanglement dynamics of a pure state composed of two parts, initially prepared in a product of coherent states and governed by a generic Hamiltonian. In this scenario, the linear entropy of the reduced state, our entanglement quanti?er, was shown to be written, in the short-time regime, in terms of a real trajectory of the underlying classical dynamics. We extend this semiclassical result by demonstrating that it is possible to include complex trajectories in the calculation. This strategy contributes to improving the previous approximation, extending its accuracy for longer values of time. We also show, for a particular Hamiltonian, a ?rst application of the achieved formula, attesting to its ef?ciency.
关键词： semiclassical approximation,entanglement,quantum dynamics,linear entropy,complex trajectories
更新于2025-09-11 14:15:04
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Finite-difference time-domain method for calculating photoexcited molecular vibration wave-packet dynamics
摘要： We propose a simple numerical calculation method for solving molecular vibrational dynamics. A finite-difference time-domain (FDTD) method is utilized to solve the Schr?dinger equation for wave packet dynamics driven by incident light pulses. Vibrational wave function is discretized and divided into real and imaginary parts, and then the Schr?dinger equation is solved by temporally and alternately calculating the real and imaginary parts, in a similar manner to the conventional FDTD method. Taking generation of a hot molecule by pump-dump scheme and multi-photon excitation process as examples, we show the validity and usefulness of the proposed method. The dynamics of the vibrational wave packets in the pump-dump scheme and transient virtual excitations of intermediate vibronic state in the three-photon absorption can be easily visualized, and the intensity dependence of excitation population for ultra-high intensity beyond the perturbation theory can be accurately calculated.
关键词： pump-dump scheme,molecular wave-packet dynamics,multi photon absorption,FDTD method for quantum dynamics
更新于2025-09-09 09:28:46
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Negative-temperature-state relaxation and reservoir-assisted quantum entanglement in double-spin-domain systems
摘要： Spin collective phenomena including superradiance are even today being intensively investigated with experimental tests performed based on state-of-the-art quantum technologies. Such attempts are not only for the simple experimental verification of predictions from the last century, but also as a motivation to explore new applications of spin collective phenomena and the coherent control of the coupling between spin ensembles and reservoirs. In this paper, we investigate the open quantum dynamics of two spin ensembles (double-spin domains) coupled to a common bosonic reservoir. We analyze in detail the dynamics of our collective state and its structure by focusing on both the symmetry and asymmetry of this coupled spin system. We find that when the spin size of one of the double domains is larger than that of the other domain, at the steady state this system exhibits two unusual collective behaviors: the negative-temperature-state relaxation in the smaller spin domain and the reservoir-assisted quantum entanglement between the two domains. These results are the consequence of the asymmetry of this system and the decoherence driven by the common reservoir.
关键词： negative-temperature-state relaxation,spin collective phenomena,bosonic reservoir,superradiance,quantum entanglement,quantum dynamics
更新于2025-09-09 09:28:46
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Any quantum network is structurally controllable by a single driving signal
摘要： Control theory concerns with the questions if and how it is possible to drive the behavior of a complex dynamical system. A system is said to be controllable if we can drive it from any initial state to any desired state in finite time. For many complex networks, the precise knowledge of system parameters lacks. But, it is possible to make a conclusion about network controllability by inspecting its structure. Classical theory of structural controllability is based on the Lin’s structural controllability theorem, which gives necessary and sufficient conditions to conclude whether a network is structurally controllable. Due to this fundamental theorem, we may identify a minimum driver vertex set, whose control with independent driving signals is sufficient to make the whole system controllable. I show that Lin’s theorem does not apply to quantum networks, if local operations and classical communication between vertices are allowed. Any quantum network can be modified to be structurally controllable obeying a single driving vertex.
关键词： Quantum networks,Linear quantum dynamics,Controllability
更新于2025-09-09 09:28:46
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Ultrafast carbon monoxide photolysis and heme spin-crossover in myoglobin via nonadiabatic quantum dynamics
摘要： Light absorption of myoglobin triggers diatomic ligand photolysis and a spin crossover transition of iron(II) that initiate protein conformational change. The photolysis and spin crossover reactions happen concurrently on a femtosecond timescale. The microscopic origin of these reactions remains controversial. Here, we apply quantum wavepacket dynamics to elucidate the ultrafast photochemical mechanism for a heme–carbon monoxide (heme–CO) complex. We observe coherent oscillations of the Fe–CO bond distance with a period of 42 fs and an amplitude of ～1 ?. These nuclear motions induce pronounced geometric reorganization, which makes the CO dissociation irreversible. The reaction is initially dominated by symmetry breaking vibrations inducing an electron transfer from porphyrin to iron. Subsequently, the wavepacket relaxes to the triplet manifold in ～75 fs and to the quintet manifold in ～430 fs. Our results highlight the central role of nuclear vibrations at the origin of the ultrafast photodynamics of organometallic complexes.
关键词： Ultrafast carbon monoxide photolysis,nonadiabatic quantum dynamics,myoglobin,heme spin-crossover
更新于2025-09-09 09:28:46
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Ultraslow Waves and Photonic Quantum Dynamics on the Nanoscale
摘要： Recent broad interest in the physics and applications of ultraslow waves in nanoscale structures range from light-waves or surface plasmons in nanoplasmonic devices to sound waves in acoustic-metamaterial waveguides, as well as plasmons and phonon polaritons in graphene and van der Waals crystals. Here we highlight that combining ultraslow waves with active photonic quantum materials opens up new domains for science, materials physics and engineering, providing the foundation for novel photonic quantum and communication technologies and nanolasing. We will outline the underlying physics of ultraslow waves on the nanoscale and discuss far-reaching opportunities resulting from a combination of ultraslow waves and active photonic quantum materials enabling single quantum emitter strong coupling. The ultrafast spatio-temporal dynamics of cavity-free stopped-light nanolasing and surface plasmon polariton condensation in nanoplasmonic heterostructures are yet further reflections of the special properties of light in the vicinity of stopped-light singularities, while a combination of stopped-light modes with epsilon-near-zero and topological materials with vanishing refractive index offer further exciting possibilities for nanophotonics.
关键词： nano-plasmonics,ultraslow waves,cavity-free nanolasing,quantum dynamics,stopped-light
更新于2025-09-09 09:28:46