- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Complete and Nondestructive Atomic Greenberger-Horne-Zeilinger-State Analysis Assisted by Invariant-Based Inverse Engineering
摘要： A protocol to realize complete and nondestructive atomic Greenberger–Horne–Zeilinger (GHZ)-state analysis in cavity quantum electrodynamics (QED) systems is presented. In this protocol, the three information-carrier atoms and the three auxiliary atoms are trapped in six separated cavities, respectively. After ten-step operations, the information for distinguishing the eight different GHZ states of the three information-carrier atoms is encoded on the auxiliary atoms. Thus, by means of detecting the auxiliary atoms, complete and nondestructive GHZ-state analysis with high success probability is realized. Moreover, the driving pulses of operations are designed as a simple superposition of Gaussian or trigonometric functions by using the invariant-based inverse engineering. Therefore, the protocol can be realized experimentally and applied in some quantum information tasks based on complete GHZ-state analysis with less physical entanglement resource.
关键词： GHZ-state analysis,cavity quantum electrodynamics system,invariant-based inverse engineering
更新于2025-09-23 15:23:52
-
Jarzynski equality for superconducting optical cavities: An alternative path to determine Helmholtz free energy
摘要： A superconducting cavity model was proposed as a way to experimentally investigate the work performed in a quantum system. We found a simple mathematical relation between the free energy variation and visibility measurement in quantum cavity context. If we consider the difference of Hamiltonian at time t0 and tλ (protocol time) as a quantum work, then the Jarzynski equality is valid and the visibility can be used to determine the work done on the cavity.
关键词： quantum Jarzynski equality,quantum heat,quantum work,cavity quantum electrodynamics
更新于2025-09-23 15:22:29
-
gauge models: Towards quantum simulations of the Schwinger-Weyl QED
摘要： We study the ground-state properties of a class of Zn lattice gauge theories in 1 + 1 dimensions, in which the gauge fields are coupled to spinless fermionic matter. These models, stemming from discrete representations of the Weyl commutator for the U(1) group, preserve the unitary character of the minimal coupling and have, therefore, the property of formally approximating lattice quantum electrodynamics in one spatial dimension in the large-n limit. The numerical study of such approximated theories is important to determine their effectiveness in reproducing the main features and phenomenology of the target theory, in view of implementations of cold-atom quantum simulators of QED. In this paper, we study the cases n = 2 ÷ 8 by means of a DMRG code that exactly implements Gauss’s law. We perform a careful scaling analysis and show that, in absence of a background field, all Zn models exhibit a phase transition which falls in the Ising universality class, with spontaneous symmetry breaking of the CP symmetry. We then perform the large-n limit and find that the asymptotic values of the critical parameters approach the ones obtained for the known phase transition of the zero-charge sector of the massive Schwinger model, which occurs at negative mass.
关键词： phase transition,Ising universality class,CP symmetry,Zn lattice gauge theories,cold-atom quantum simulators,DMRG code,quantum electrodynamics
更新于2025-09-23 15:21:21
-
Magnetic field compatible circuit quantum electrodynamics with graphene Josephson junctions
摘要： Circuit quantum electrodynamics has proven to be a powerful tool to probe mesoscopic effects in hybrid systems and is used in several quantum computing (QC) proposals that require a transmon qubit able to operate in strong magnetic fields. To address this we integrate monolayer graphene Josephson junctions into microwave frequency superconducting circuits to create graphene based transmons. Using dispersive microwave spectroscopy we resolve graphene’s characteristic band dispersion and observe coherent electronic interference effects confirming the ballistic nature of our graphene Josephson junctions. We show that the monoatomic thickness of graphene renders the device insensitive to an applied magnetic field, allowing us to perform energy level spectroscopy of the circuit in a parallel magnetic field of 1 T, an order of magnitude higher than previous studies. These results establish graphene based superconducting circuits as a promising platform for QC and the study of mesoscopic quantum effects that appear in strong magnetic fields.
关键词： transmon qubit,magnetic field resilience,quantum computing,Circuit quantum electrodynamics,graphene Josephson junctions
更新于2025-09-23 15:21:01
-
Amplification and cross-Kerr nonlinearity in waveguide quantum electrodynamics
摘要： We explore amplification and cross-Kerr nonlinearity by a three-level emitter (3LE) embedded in a waveguide and driven by two light beams. The coherent amplification and cross-Kerr nonlinearity were demonstrated in recent experiments, respectively, with a V and a ladder-type 3LE coupled to an open superconducting transmission line carrying two microwave fields. Here, we consider (cid:2), V, and ladder-type 3LE, and compare the efficiency of coherent and incoherent amplification as well as the magnitude of the cross-Kerr phase shift in all three emitters. We apply the Heisenberg-Langevin equations approach to investigate the scattering of a probe and a drive beam, both initially in coherent states. We particularly calculate the regime of the probe and drive powers when the 3LE acts most efficiently as a coherent amplifier and derive the second-order coherence of amplified probe photons. Finally, we apply the Kramers-Kronig relations to correlate the amplitude and phase response of the probe beam, which are used in finding the coherent amplification and the cross-Kerr phase shift in these systems.
关键词： waveguide quantum electrodynamics,three-level emitter,cross-Kerr nonlinearity,amplification,Heisenberg-Langevin equations,Kramers-Kronig relations
更新于2025-09-23 15:21:01
-
The Unified Theory of Resonance Energy Transfer According to Molecular Quantum Electrodynamics
摘要： An overview is given of the molecular quantum electrodynamical (QED) theory of resonance energy transfer (RET). In this quantized radiation field description, RET arises from the exchange of a single virtual photon between excited donor and unexcited acceptor species. Diagrammatic time-dependent perturbation theory is employed to calculate the transfer matrix element, from which the migration rate is obtained via the Fermi golden rule. Rate formulae for oriented and isotropic systems hold for all pair separation distances, R, beyond wave function overlap. The two well-known mechanisms associated with migration of energy, namely the R?6 radiationless transfer rate due to F?rster and the R?2 radiative exchange, correspond to near- and far-zone asymptotes of the general result. Discriminatory pair transfer rates are also presented. The influence of an environment is accounted for by invoking the polariton, which mediates exchange and by introducing a complex refractive index to describe local field and screening effects. This macroscopic treatment is compared and contrasted with a microscopic analysis in which the role of a neutral, polarizable and passive third-particle in mediating transfer of energy is considered. Three possible coupling mechanisms arise, each requiring summation over 24 time-ordered diagrams at fourth-order of perturbation theory with the total rate being a sum of two- and various three-body terms.
关键词： molecular quantum electrodynamics,virtual photon exchange,resonance energy transfer,discriminatory transfer,F?rster transfer,medium effects,polariton mediated exchange,radiative exchange
更新于2025-09-23 15:21:01
-
Coupling Rydberg Atoms to Microwave Fields in a Superconducting Coplanar Waveguide Resonator
摘要： Rydberg helium atoms traveling in pulsed supersonic beams have been coupled to microwave fields in a superconducting coplanar waveguide (CPW) resonator. The atoms were initially prepared in the 1s55s 3S1 Rydberg level by two-color two-photon laser excitation from the metastable 1s2s 3S1 level. Two-photon microwave transitions between the 1s55s 3S1 and 1s56s 3S1 levels were then driven by the 19.556 GHz third-harmonic microwave field in a quarter-wave CPW resonator. This superconducting microwave resonator was fabricated from niobium nitride on a silicon substrate and operated at temperatures between 3.65 and 4.30 K. The populations of the Rydberg levels in the experiments were determined by state-selective pulsed electric field ionization. The coherence of the atom-resonator coupling was studied by time-domain measurements of Rabi oscillations.
关键词： quantum electrodynamics,Rydberg atoms,microwave fields,superconducting coplanar waveguide resonator
更新于2025-09-23 15:21:01
-
Virtual Photons: From the Lamb Shift to Black Holes
摘要： While virtual processes are a well-known feature of quantum electrodynamics, the role of virtual photons—in phenomena ranging from the microscopic to the cosmic—is less generally appreciated.
关键词： virtual photons,Unruh radiation,black holes,Lamb shift,quantum electrodynamics,Hawking radiation
更新于2025-09-23 15:21:01
-
Topological and nontopological photonic states in two coupled circuit quantum electrodynamics chains
摘要： We investigate the topological and nontopological photonic states induced by the interchain coupling strength in a one-dimensional coupled circuit quantum electrodynamics chains system. In the case of strong coupling strength, we find that the original topologically nontrivial interface states of the system gradually disappear and finally become two nontopological impurity states. Meanwhile, two new topologically nontrivial interface states appear next to the two middle resonators. The processes can be clearly delineated by the energy eigenvalue spectrum and the state distributions of the system. Moreover, we present the phase diagram to illustrate the characteristics of phase transition of the system. Assisted by the lattice-based cavity input-output process, we can measure these photonic states, which are either localized or extended, in the steady state condition. Our scheme would be feasible for experimental implementation of topological and nontopological photonic states with the current physical system.
关键词： topological phase,circuit quantum electrodynamics,nontopological impurity state,Su–Schrieffer–Heeger model
更新于2025-09-23 15:19:57
-
Three-player polaritons: nonadiabatic fingerprints in an entangled atom-molecule-photon system
摘要： A quantum system composed of a molecule and an atomic ensemble, con?ned in a microscopic cavity, is investigated theoretically. The indirect coupling between atoms and the molecule, realized by their interaction with the cavity radiation mode, leads to a coherent mixing of atomic and molecular states. It is shown for the Na2 molecule that by changing the cavity wavelength and the molecular states, and at strong enough cavity ?eld strengths hybrid atom-molecule-photon polaritons are formed. Moreover, an unforeseen intensity borrowing e?ect, which can be seen as a strong nonadiabatic ?ngerprint, is identi?ed in the atomic transition peak, originating from the contamination of the atomic excited state with excited molecular rovibronic states.
关键词： nonadiabatic,entangled atom-molecule-photon system,intensity borrowing effect,polaritons,cavity quantum electrodynamics
更新于2025-09-23 15:19:57