Environment-Assisted Shortcuts to Adiabaticity

Envariance is a symmetry exhibited by correlated quantum systems. Inspired by this “quantum fact of life,” we propose a novel method for shortcuts to adiabaticity, which enables the system to evolve through the adiabatic manifold at all times, solely by controlling the environment. As the main results, we construct the unique form of the driving on the environment that enables such dynamics, for a family of composite states of arbitrary dimension. We compare the cost of this environment-assisted technique with that of counterdiabatic driving, and we illustrate our results for a two-qubit model.     

Population Transfer in a Nitrogen-Vacancy Spin Qutrit via Shortcuts to Adiabaticity with Simplified Drivings

JETP Letters - Optimal control of quantum system is significant for information science and technology. Here, an efficient scheme is proposed for implementing fast population transfer in a spin...     

Nonleaky Population Transfer in a Transmon Qutrit via Largely-Detuned Drivings

We propose an efficient scheme to implement nonleaky population transfer in a transmon qutrit via largely-detuned drivings. Due to weak level anharmonicity of the transmon system, the remarkable quantum leakages need to be considered in quantum coherent operations. Under the conditions of two-photon resonance and large detunings, the robust population transfer within a qutrit can be implemented via the technique of stimulated Raman adiabatic passage. Based on the accessible parameters, the feasible approach can remove the leakage error effectively, and then provides a potential approach for enhancing the transfer fidelity with transmon-regime artificial atoms experimentally.     

Information Storage and Retrieval in a Photon-Spin System Via Shortcut Drivings

Quantum-information storage and retrieval in an optimized manner are of significance to information processing with composite systems. In this paper, an effective scheme is proposed for performing rapid information storage and retrieval between microwave photons and a nitrogen-vacancy electron spin via shortcuts to adiabaticity. A qutrit of composite photon-spin system interacts with two classical drivings. By modifying two original Rabi drivings, instead of directly adding an auxiliary counter-diabatic interaction, information storage and retrieval can be rapidly performed with the optimized shortcut dynamics. Benefited from the shorter duration time, the shortcut-based operation is more insensitive to decoherence effects than that of adiabatic counterpart. This strategy provides a promising avenue toward fast and robust information processing with solid-state hybrid systems.     

Improving Shortcuts to Non‐Hermitian Adiabaticity for Fast Population Transfer in Open Quantum Systems

It is still a challenge to experimentally realize shortcuts to adiabaticity (STA) for a non‐Hermitian quantum system since a non‐Hermitian quantum system's counterdiabatic driving Hamiltonian contains some unrealizable auxiliary control fields. In this paper, we relax the strict condition in constructing STA and propose a method to redesign a realizable supplementary Hamiltonian to construct non‐Hermitian STA. The redesigned supplementary Hamiltonian can be eithersymmetric or asymmetric. For the sake of clearness, we apply this method to an Allen‐Eberly model as an example to verify the validity of the optimized non‐Hermitian STA. The numerical simulation demonstrates that a ultrafast population inversion could be realized in a two‐level non‐Hermitian system.     

Robust Preparation of Atomic Concatenated Greenberger–Horne–Zeilinger States via Shortcuts to Adiabaticity

Here, a protocol for robust preparation of an atomic concatenated Greenberger–Horne–Zeilinger (C‐GHZ) state via shortcuts to adiabaticity (STA) is proposed. The devices for implementing the protocol consist of atoms, cavities, and the optical fibers, which are feasible with current technology. The atoms are trapped in the separated cavities allowing individual control over each atom with classical fields. STA helps to design Rabi frequencies of classical fields so that the atoms can be driven from the initial states to the target states. The numerical simulations show that the protocol holds robustness against atomic spontaneous emissions and photonic leakages. Thus, the protocol may be realized by experiments in the near future.     

Shortcut-to-Adiabaticity-Like Techniques for Parameter Estimation in Quantum Metrology

Quantum metrology makes use of quantum mechanics to improve precision measurements and measurement sensitivities. It is usually formulated for time-independent Hamiltonians, but time-dependent Hamiltonians may offer advantages, such as a T4 time dependence of the Fisher information which cannot be reached with a time-independent Hamiltonian. In Optimal adaptive control for quantum metrology with time-dependent Hamiltonians (Nature Communications 8, 2017), Shengshi Pang and Andrew N. Jordan put forward a Shortcut-to-adiabaticity (STA)-like method, specifically an approach formally similar to the “counterdiabatic approach”, adding a control term to the original Hamiltonian to reach the upper bound of the Fisher information. We revisit this work from the point of view of STA to set the relations and differences between STA-like methods in metrology and ordinary STA. This analysis paves the way for the application of other STA-like techniques in parameter estimation. In particular we explore the use of physical unitary transformations to propose alternative time-dependent Hamiltonians which may be easier to implement in the laboratory.     

Fast Driving of a Particle in Two Dimensions without Final Excitation

Controlling the motional state of a particle in a multidimensional space is key for fundamental science and quantum technologies. Applying a recently found two-dimensional invariant combined with linear invariants, we propose protocols to drive a particle in two dimensions so that the final harmonic trap is translated and rotated with respect to the initial one. These protocols realize a one-to-one mapping between initial and final eigenstates at some predetermined time and avoid any final excitations.     

基于绝热捷径的两原子相位门设计

基于绝热捷径技术,我们提出了一个通过设计共振脉冲,仅用一个操作步骤便实现两原子相位门的理论方案。我们讨论了原子自发辐射和腔中光子泄漏对方案的影响,数值结果表明当前方案对上面的两种耗散效应和试验参数的误差都具有鲁棒性。此外,本方案所需的演化时间非常短并且在整个演化过程中都不需要额外引入复杂的脉冲。因此,这个方案在当前实验条件下是比较容易实现的。     

Highly efficient charging and discharging of three-level quantum batteries through shortcuts to adiabaticity

Quantum batteries are energy storage devices that satisfy quantum mechanical principles. How to improve the battery’s performance such as stored energy and power is a crucial element in the quantum battery. Here, we investigate the charging and discharging dynamics of a three-level counterdiabatic stimulated Raman adiabatic passage quantum battery via shortcuts to adiabaticity, which can compensate for undesired transitions to realize a fast adiabatic evolution through the application of an additional control field to an initial Hamiltonian. The scheme can significantly speed up the charging and discharging processes of a three-level quantum battery and obtain more stored energy and higher power compared with the original stimulated Raman adiabatic passage. We explore the effect of both the amplitude and the delay time of driving fields on the performances of the quantum battery. Possible experimental implementation in superconducting circuit and nitrogen–vacancy center is also discussed.     

Speeding up the Generation of Entangled State between a Superconducting Qubit and Cavity Photons via Counterdiabatic Driving

Optimal generation of entangled states is of critical significance for robust quantum information processing. An effective scheme is presented for speeding up the generation of an entangled state between a superconducting qubit and microwave photons via counterdiabatic driving. At a magic bias point, the first three levels of a charge-phase quantum circuit constitute an effective qutrit. An entangled state based on adiabatic population transfer is first achieved. By the technique of shortcuts to adiabaticity, a counterdiabatic driving is applied to the qutrit, which then accelerates the entanglement generation significantly. Moreover, with the accessible decoherence rates, the rapid operations in a shortcut way are highly robust when compared with adiabatic manipulations. The scheme could offer a promising approach toward optimal preparation of entangled states with superconducting artificial atoms in circuit quantum electrodynamics, experimentally.     

Shortcut-based quantum gates on superconducting qubits in circuit QED

Construction of optimal gate operations is significant for quantum computation. Here an efficient scheme is proposed for performing shortcut-based quantum gates on superconducting qubits in circuit quantum electrodynamics (QED). Two four-level artificial atoms of Cooper-pair box circuits, having sufficient level anharmonicity, are placed in a common quantized field of circuit QED and are driven by individual classical microwaves. Without the effect of cross resonance, one-qubit NOT gate and phase gate in a decoupled atom can be implemented using the invariant-based shortcuts to adiabaticity. With the assistance of cavity bus, a one-step SWAP gate can be obtained within a composite qubit-photon-qubit system by inversely engineering the classical drivings. We further consider the gate realizations by adjusting the microwave fields. With the accessible decoherence rates, the shortcut-based gates have high fidelities. The present strategy could offer a promising route towards fast and robust quantum computation with superconducting circuits experimentally.     

Noncyclic nonadiabatic holonomic quantum gates via shortcuts to adiabaticity

High-fidelity quantum gates are essential for large-scale quantum computation. However, any quantum manipulation will inevitably affected by noises, systematic errors and decoherence effects, which lead to infidelity of a target quantum task. Therefore, implementing high-fidelity, robust and fast quantum gates is highly desired. Here, we propose a fast and robust scheme to construct high-fidelity holonomic quantum gates for universal quantum computation based on resonant interaction of three-level quantum systems via shortcuts to adiabaticity. In our proposal, the target Hamiltonian to induce noncyclic non-Abelian geometric phases can be inversely engineered with less evolution time and demanding experimentally, leading to high-fidelity quantum gates in a simple setup. Besides, our scheme is readily realizable in physical system currently pursued for implementation of quantum computation. Therefore, our proposal represents a promising way towards fault-tolerant geometric quantum computation.     

利用布居囚禁态实现高效率布居转移

利用缀饰原子方法研究了激光同位素分离涉及的一个四能级系统的布居转移过程，发现了类似于三能级系统的布居囚禁态，在此基础上分析了光泵浦过程的布居囚禁现象，提出一种能够利用基态布居及亚稳态热布居的高效率光泵浦方法并以分离轴原子为例说明该方法的优越性。     

Population Transfer of U Vapor Effected by the Population of a Trapped State

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Acceleration of adiabatic quantum state transfer in a spin chain under zero-energy-change pulse control

We present a protocol for accelerating adiabatic quantum state transfer through a spin chain by adding an effective control pulse. Using Feshbach P-Q partitioning technique, we obtain the one-component dynamical equation which guides us to set the amplitude and period of the control field. This field can be a sequence of alternatively negative and positive (zero-energy change) pulses which can be realized easily in experiment. As an example, we discuss a three particles spin chain and the numerical calculation shows that the accelerated quantum state transfer can be obtained.     

准Λ型四能级中用非匹配高斯脉冲实现相干布居转移

文章研究用非匹配高斯脉冲实现四能级准Λ型系统中的相干布居转移.从密度矩阵方程出发,对四个态的布居数随时间的演化进行了数值模拟.模拟结果表明,泵浦光场的拉比频率强度和失谐量对布居转移率的影响和探测光场、耦合光场的拉比频率强度及失谐量对布居转移率的影响不同;自发辐射诱导相干(SGC)对布居转移率的影响不大.但当它们选取适当参数的时候,基态的布居几乎可以全部被转移到目标态能级.     

Population coherent control of a Rydberg sodium atom in a microwave field

The B-spline expansion technique and the time-dependent multilevel approach (TDMA) are used to study the interaction between a microwave field and sodium atoms. The Rydberg sodium atom energy levels of p states in zero field are calculated, and the results are in good agreement with the other theoretical ones. The time evolutions during the population transfers of the five states from n = 75 to n = 79 in different microwave fields are obtained. The results show that the coherent control of the population transfer from the lower states to the higher ones can be accomplished by optimizing the microwave pulse parameters.     

Lie transformation on shortcut to adiabaticity in parametric driving quantum systems

Shortcut to adiabaticity(STA) is a speedway to produce the same final state that would result in an adiabatic, infinitely slow process. Two typical techniques to engineer STA are developed by either introducing auxiliary counterdiabatic fields or finding new Hamiltonians that own dynamical invariants to constraint the system into the adiabatic paths. In this paper,an efficient method is introduced to naturally cover the above two techniques with a unified Lie algebraic framework and neatly remove the design difficulties and loose assumptions in the two techniques. A general STA scheme for different potential expansions concisely achieves with the aid of squeezing transformations.     

Population transfer of sodium in a single analytical laser pulse

The population transfer of sodium in a single analytical laser pulse was studied in three models:two-level sodium,three-level sodium and many-level sodium.The effect of a third state on a two-level system was studied by investigating a ladder three-level system.Two effects were found in the vicinity of the resonance frequency.