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In this paper, we introduce the amplified thermal state (ATS) by operating (g − 1) n ̂ + 1 on the thermal state (TS). Here, g > 1 is the amplification factor and n ̂ is the photon number operator. We study its properties, such as light intensity, signal-to-noise ratio (SNR), Fock matrix elements and Wigner function. In addition, we study its decoherence in photon-loss channel by analyzing evolution of all above properties. All considered properties are derived analytically and simulated numerically. Compared with the original TS, the amplification can enhance light intensity and SNR, remain the mixed character, and exhibit non-Gaussianity. While the decoherence will weaken light intensity and SNR, remain the mixed character, and return to Gaussian state. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Optimal population transfer is of critical importance for quantum information processing. Here an efficient scheme is proposed for implementing controllable and shortcut-based population transfers with a nitrogen-vacancy (NV) electron spin and cavity photons. The electron spin is placed inside a setup of circuit quantum electrodynamics (QED). Under a suitable magnetic field bias, the ground state of electron spin constitutes an effective triplet. By means of the quantized cavity field and classical drivings, we obtain a Δ -configuration interaction within a composite three-state system. Based on the adjustable Rabi couplings, the shortcut-based population transfers can be performed controllably. Moreover, compared with the adiabatic counterparts, the operations assisted by counter-diabatic drivings need much shorter times and then are less susceptible to decoherence effects. Our scheme provides a promising avenue toward optimized transfer operations on NV center electron spins in circuit QED. [ABSTRACT FROM AUTHOR]

Entanglement generation via optimal drivings is of significance for quantum information science and engineering. Here, an efficient scheme is proposed for creating entangled states between two transmon qubits via shortcuts to adiabaticity with constant Rabi drivings. Two three-level atoms of Cooper-pair box circuits are coupled to a common cavity field of transmission-line resonator and individually driven by adjustable classical microwaves. In the regime of large detuning, we obtain an effective three-state system consisting of qubits and cavity photons. By the invariant-based shortcuts with time-independent Rabi drivings, two-qubit entangled states can be rapidly induced from an easily prepared product state. Compared to the entanglement creation with time-dependent Rabi drivings, our protocol not only becomes more feasible in experiment but also needs shorter times. Moreover, high-fidelity quantum operations can be realized with the accessible decoherence rates. The scheme could pave a promising avenue towards optimal generation of entangled states between superconducting qubits. [ABSTRACT FROM AUTHOR]

We study the symmetry, magnetization, temperature and electrostatic gating effect on the selective spin-valley polarized transport through the zigzag silicene nanoribbon (ZSiNR) coupled to two ferromagnetic (FM) leads, which are supposed to be in either parallel (P) or anti-parallel (AP) configuration. The transport properties show evident even-odd behavior and are not affected by the zigzag-chain number N when |EF|M. When |EF|V0. As the temperature rises, the spin/valley dependent conductance and the spin-valley polarization are smoothed. The above results have potential applications in fabricating spin-valleytronic devices based on FM-normal-FM ZSiNR junctions. [ABSTRACT FROM AUTHOR]

Optimal two-qubit operation is of significance to quantum information processing. An efficient scheme is proposed for realizing the shortcut to adiabatic two-qubit state swap in a superconducting circuit quantum electrodynamics (QED) via effective drivings. Two superconducting qutrits are coupled to a common cavity field and individual classical drivings. Based on two Gaussian-type Rabi drivings, two-qubit state swap can be adiabatically implemented within a reduced three-state system. To speed up the operation, these two original Rabi drivings are modified in the framework of shortcuts to adiabaticity, instead of adding an extra counterdiabatic driving. Moreover, owing to a shorter duration time, the decoherence effects on the accelerated quantum operation can be mitigated significantly. The strategy could offer an optimized method to construct fast and robust quantum operations on superconducting qubits experimentally. [ABSTRACT FROM AUTHOR]

Optimal creation of photon Fock states is of importance for quantum information processing and state engineering. Here an efficient strategy is presented for speeding up generation of photon Fock state in a superconducting circuit via counterdiabatic driving. A transmon qubit is dispersively coupled to a quantized electrical field. We address a Λ-configuration interaction between the composite system and classical drivings. Based on two Gaussian-shaped drivings, a single-photon Fock state can be generated adiabatically. Instead of adding an auxiliary counterdiabatic driving, our concern is to modify these two Rabi drivings in the framework of shortcut to adiabaticity. Thus an accelerated operation with high efficiency can be realized in a much shorter time. Compared with the adiabatic counterpart, the shortcut-based operation is significantly insusceptible to decoherence effects. The scheme could offer a promising way to deterministically prepare photon Fock states with superconducting quantum circuits. [ABSTRACT FROM AUTHOR]

Intestinal fatty-acid binding protein (I-FABP, also called FABP2) is involved in the uptake of dietary fatty acids in the intestine, and its binding specificity is only with long-chain fatty acid. In this study, sequences of 4 exons in pigeon FABP2 were successfully amplified. The encoded protein had a molecular weight of 15.13 kDa and the theoretical pI was 6.75. Bioinformatics analysis indicated that the protein was predicted to contain 10 potential phosphorylation sites and did not contain signal peptide structure. The evolutionary analysis suggested the amino acid sequence of pigeon FABP2 was closest to the mallard (Nippoia nippon) homologs. Meanwhile the expression of FABP2 mRNA in different ages and tissues we conducted. It showed that the expression of the FABP2 gene was the highest in the liver, followed by the small intestine and adipose tissue, while lowest in the breast muscle. Also, the expression level in the gizzard was gradually increased with aging. Our results may serve as reference to better studies of the functional characterization and structure of the FABP2 in pigeon. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]