Abstract In this paper, we propose a protocol to accelerate a weak nonlinear quantum process: a single photon simultaneously excites two atoms using shortcut to adiabaticity. We consider a physical model composed of a transmission-line resonator and two flux qubits, where the frequency of the resonator is approximately equal to the sum of the frequencies of the two qubits. Using unitary transformation and a series of approximate methods, the system can be reduced to an equivalent two-level model. Since this transition is a weak high-order process, it is relatively sensitive to errors and decoherence. To overcome the flaws, we use the shortcut to adiabaticity method based on Lewis–Riesenfeld invariant for inverse engineering of the effective Hamiltonian, so that the transition rate can be accelerated. The robustness of the system against noise and decoherence can be improved. Therefore, the protocol we proposed can be applicable to quantum information processing and quantum optics in the microwave regime.
Abstract In this paper, we propose a protocol to accelerate a weak nonlinear quantum process: a single photon simultaneously excites two atoms using shortcut to adiabaticity. We consider a physical model composed of a transmission-line resonator and two flux qubits, where the frequency of the resonator is approximately equal to the sum of the frequencies of the two qubits. Using unitary transformation and a series of approximate methods, the system can be reduced to an equivalent two-level model. Since this transition is a weak high-order process, it is relatively sensitive to errors and decoherence. To overcome the flaws, we use the shortcut to adiabaticity method based on Lewis–Riesenfeld invariant for inverse engineering of the effective Hamiltonian, so that the transition rate can be accelerated. The robustness of the system against noise and decoherence can be improved. Therefore, the protocol we proposed can be applicable to quantum information processing and quantum optics in the microwave regime.
Abstract We propose an efficient scheme for microwave-to-optical quantum frequency conversion mediated by a single atom simultaneously coupled to a superconducting microwave resonator and an optical cavity. The atom mediates efficient interactions between the two electromagnetic modes via non-linear frequency mixing owing to the presence of huge microwave transition dipole moments between nearby Rydberg states as well as suitable optical transitions between low-lying states. In the regime of four-wave mixing with off-resonant fields, the excited states can be adiabatically eliminated, leading to an effective Hamiltonian that directly describes the two-mode interaction responsible for the frequency conversion. However, in this regime, the converter is slow, hence sensitive to losses due to cavity decays. To enhance the performance of the conversion process, we employ pulse engineering to tailor the atom-field couplings. The resulting protocol exhibits high robustness against decoherence and parameter fluctuations, making it well suited for realistic experimental implementations. Our scheme provides a promising route toward high-fidelity and scalable hybrid quantum interfaces connecting superconducting and optical quantum networks.
Abstract Optimal generation of photon Fock states is of significance to quantum science and technology. Here we develop a theoretical scheme for fast generating microwave photon Fock states in a circuit quantum electrodynamics (QED) via invariant-based shortcuts to adiabaticity. A superconducting transmon qubit is dispersively coupled to a cavity field of transmission line resonator. Two classical drivings are applied to a composite system, consisting of a transmon qubit and cavity field. In the two-photon resonance with a large intermediate-level detuning, a single-photon Fock state can be fast created by inversely engineering Rabi couplings. With the assistance of auxiliary driving, qubit state can be initialized for inducing multi-photon Fock states in the shortcut manner. Due to negligible leakage effects and high robustness, our scheme offers a potential way to rapidly prepare photon Fock states with a superconducting qubit in circuit QED.
ABSTRACT We propose and theoretically demonstrate a tailored shortcut to adiabaticity for accelerating the two‐photon Landau‐Zener‐Stückelberg‐Majorana (LZSM) transition in a superconducting transmon qutrit. Unlike conventional single‐photon LZSM processes, the two‐photon variant involves a virtual intermediate state and arises from a constrained three‐level dynamics with weak anharmonicity, leading to a nonlinear dependence of the effective Rabi coupling on the drive amplitude and stringent requirements on frequency modulation. Using the Lewis‐Riesenfeld invariant method, we construct an exact dynamical invariant for implementing a two‐photon LZSM transition with experimentally feasible, time‐dependent amplitude, and frequency modulation profiles that steer the system along an invariant eigenstate. Our protocol achieves high‐fidelity population transfer from the ground state to the second excited state in just ns, over faster than the reference adiabatic scheme. Crucially, the shortcut preserves the inherent robustness of the LZSM process against drive amplitude errors and exhibits enhanced resilience to decoherence due to the shortened operation time. This work provides a general and practical framework for accelerating higher‐order quantum transitions in multilevel systems, with direct relevance to ultrafast qudit control and scalable quantum information processing.
The coherent process that a single photon simultaneously excites two qubits has recently been theoretically predicted by Garziano et al. [L. Garziano, V. Macr\`{\i}, R. Stassi, O. Di Stefano, F. Nori, and S. Savasta, One Photon Can Simultaneously Excite two or More Atoms, Phys. Rev. Lett. 117, 043601 (2016)]. We propose a different approach to observe a similar dynamical process based on a superconducting quantum circuit, where two coupled flux qubits longitudinally interact with the same resonator. We show that this simultaneous excitation of two qubits (assuming that the sum of their transition frequencies is close to the cavity frequency) is related to the counter-rotating terms in the dipole-dipole coupling between two qubits, and the standard rotating-wave approximation is not valid here. By numerically simulating the adiabatic Landau-Zener transition and Rabi-oscillation effects, we clearly verify that the energy of a single photon can excite two qubits via higher-order transitions induced by the longitudinal couplings and the counter-rotating terms. Compared with previous studies, the coherent dynamics in our system only involves one intermediate state and, thus, exhibits a much faster rate. We also find transition paths which can interfere. Finally, by discussing how to control the two longitudinal-coupling strengths, we find a method to observe both constructive and destructive interference phenomena in our system.
By definition, quantum adiabatic process means a slow process which allows the state to follow the instantaneous eigenstates of time-dependent Hamiltonian. For some reasons, for example, to avoid the decoherence effects, or to implement large-scale quantum information processing, we may want to speed up the adiabatic process, that is, to achieve the adiabatic-like control but in very short time. In this talk, we present new methods to speeded-up expansion and transport of cold atoms in a harmonic trap. Such shortcuts to adiabaticity provide the fast expansion or transport, in which the final atomic state is the same as in the adiabatic process, but in arbitrarily short time, keeping the same populations of vibrational levels in the initial and final trap. These methods can also be generalized to Bose-Einstein Condensates. Moreover, we present shortcuts to adiabatic passage from one internal atomic state to another in twoor three-level atoms. In detail, we can apply Berry’s transitionless quantum driving method and invariant-based inverse engineering method to accelerate the Rapid Adiabatic Passage (RAP) and Stimulated Raman Adiabatic Passage (STIRAP) in twoand three-level atomic systems, respectively. We also examine and compare the stability of different schemes concerning different types of noise and system errors. Finally, we show that the technique of shortcuts to adiabaticity in two-level system can be applied in fast and robust spin flip in a quantum dot, to avoid the decoherent effects.
We propose a scheme for generating 3D entanglement between two atoms trapped in two spatially separated cavities, respectively, via shortcuts to adiabatic passage based on the approach of Lewis–Riesenfeld invariants in cavity quantum electronic dynamics. By combining Lewis–Riesenfeld invariants with quantum Zeno dynamics, we can generate 3D entanglement of the two atoms with high fidelity. The numerical simulation results show that the scheme is robust against the decoherence caused by the photon leakage and atomic spontaneous emission.