Psychological adaptation during acculturation was studied among 68 Chinese sojourners (students and visiting scholars from China and Hong Kong), 28 Chinese immigrant and Chinese‐Canadian students, 30 Chinese students and scholars in China, and 33 non‐Chinese Canadian students. Each participant completed questionnaires pertaining to various aspects of their lives and personalities, including: health beliefs and behaviours; problems and ways of coping; social contact and acculturation attitudes; psychological and physical health; and subjective adaptation. The Chinese sojourners reported lower English fluency, lower ease of making friendships, more adaptation and communication problems, and lower subjective adaptation than non‐Chinese Canadian, or Chinese‐Canadian students. The Chinese sojourners experienced less desired and actual contact, more contact incongruity, more separation and less assimilation than Chinese‐Canadian students. The Chinese sojourners reacted to their problems with less wishful thinking and self‐blame, and more tension reduction, and the seeking of informational support than non‐Chinese Canadian students. There were significant differences between groups in health concept and health causation, and believed and utilized health ways. Health causation, and believed and utilised health ways were the most important factors influencing the Chinese sojourners' health status. The Chinese sojourners experienced more problems, but tended to use fewer health ways after‐arrival than pre‐departure. The Chinese also experienced poorer health, especially poorer psychological health after‐arrival than pre‐departure. The longitudinal and cross‐sectional analysis of the Chinese sojourners' Cawte scores supported the U‐curve hypothesis.

Non-adiabatic holonomic quantum computation (NHQC) has been developed to shorten the construction times of geometric quantum gates. However, previous NHQC gates require the driving Hamiltonian to satisfy a set of rather restrictive conditions, reducing the robustness of the resulting geometric gates against control errors. Here we show that non-adiabatic geometric gates can be constructed in an extensible way, called NHQC+, for maintaining both flexibility and robustness. Consequently, this approach makes it possible to incorporate most of the existing optimal control methods, such as dynamical decoupling, composite pulses, and shortcut to adiabaticity, into the construction of single-looped geometric gates. Furthermore, this extensible approach of geometric quantum computation can be applied to various physical platform such as superconducting qubits and nitrogen-vacancy centers. Specifically, we performed numerical simulation to show how the noise robustness in the recent experimental implementations [Phys. Rev. Lett. 119, 140503 (2017)] and [Nat. Photonics 11, 309 (2017)] can be significantly improved by our NHQC+ approach. These results cover a large class of new techniques combing the noise robustness of both geometric phase and optimal control theory.

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Faithfully transferring quantum state is essential for quantum information processing. Here, we demonstrate a fast (in 84 ns) and high-fidelity (99.2%) transfer of arbitrary quantum states in a chain of four superconducting qubits with nearest-neighbor coupling. This transfer relies on full control of the effective couplings between neighboring qubits, which is realized only by parametrically modulating the qubits without increasing circuit complexity. Once the couplings between qubits fulfill specific ratio, a perfect quantum state transfer can be achieved in a single step, therefore robust to noise and accumulation of experimental errors. This quantum state transfer can be extended to a larger qubit chain and thus adds a desirable tool for future quantum information processing. The demonstrated flexibility of the coupling tunability is suitable for quantum simulation of manybody physics which requires different configurations of qubit couplings.

Searching topological states in artificial systems has recently become a rapidly growing field of research. Meanwhile, significant experimental progresses on observing topological phenomena have been made in superconducting circuits. However, topological insulator states have not yet been reported in this system. Here, for the first time, we experimentally realize a tunable dimerized spin chain model and observe the topological magnon insulator states in a superconducting qubit chain. Via parametric modulations of the qubit frequencies, we show that the qubit chain can be flexibly tuned into topologically trivial or nontrivial magnon insulator states. Based on monitoring the quantum dynamics of a single-qubit excitation in the chain, we not only measure the topological winding numbers, but also observe the topological magnon edge and defect states. Our experiment exhibits the great potential of tunable superconducting qubit chain as a versatile platform for exploring non-interacting and interacting symmetry-protected topological states. arXiv:1901.05683v2 [quant-ph]

Geometric phases are noise resilient, and thus provide a robust way towards high-fidelity quantum manipulation. Here we experimentally demonstrate arbitrary nonadiabatic holonomic single-qubit quantum gates for both a superconducting transmon qubit and a microwave cavity in a single-loop way. In both cases, an auxiliary state is utilized, and two resonant microwave drives are simultaneously applied with well-controlled but varying amplitudes and phases for the arbitrariness of the gate. The resulting gates on the transmon qubit achieve a fidelity of 0.996 characterized by randomized benchmarking and the ones on the cavity show an averaged fidelity of 0.978 based on a full quantum process tomography. In principle, a nontrivial two-qubit holonomic gate between the qubit and the cavity can also be realized based on our presented experimental scheme. Our experiment thus paves the way towards practical nonadiabatic holonomic quantum manipulation with both qubits and cavities in a superconducting circuit.

The implementation of holonomic quantum computation on superconducting quantum circuits is challenging due to the general requirement of controllable complicated coupling between multilevel systems. Here we solve this problem by proposing a scalable circuit QED lattice with simple realization of a universal set of nonadiabatic holonomic quantum gates. Compared with the existing proposals, we can achieve both the single and two logical qubit gates in an tunable and all-resonant way through a hybrid transmon-transmission-line encoding of the logical qubits in the decoherence-free subspaces. This distinct advantage thus leads to quantum gates with very fast speeds and consequently very high fidelities. Therefore, our scheme paves a promising way towards the practical realization of high-fidelity nonadiabatic holonomic quantum computation.Comment: v2: thoroughly rewritten version with major revission; v3: Accepted by PRA; V4: Published versio

We propose two schemes for the generation of the cluster states. One is based on cavity quantum electrodynamics (QED) techniques. The scheme only requires resonant interactions between two atoms and a singlemode cavity. The interaction time is very short, which is important in view of decoherence. Furthermore, we also discuss the cavity decay and atomic spontaneous emission case. The other is based on atomic ensembles. The scheme has inherent fault tolerance function and is robust to realistic noise and imperfections. All the facilities used in our schemes are well within the current technology.