Journal of Experimental and Theoretical Physics最新文献

Standard methods of laser cooling ¹⁷¹Yb⁺ in a radiofrequency trap involve the use of coherent optical fields resonant to the optical transition of the ²S_1/2 → ²P_1/2 line, as well as a magnetic field that is used to destroy the coherent population trapping (CPT) appeared at the ²S_1/2(F = 1) level. Further precision measurements with use of the clock transitions (quadrupole ²S_1/2(F = 0) → ²D_3/2(F = 2) and octupole ²S_1/2(F = 0) → ²F_7/2(F = 2)) require significant suppression and control of residual magnetic fields. In this work, we investigate in detail an alternative method of laser cooling ¹⁷¹Yb⁺ with use of polychromatic fields, which allows completely eliminate the use of a magnetic field in the ion cooling process and thus suppress Zeeman quadratic shift associated with uncontrolled residual magnetic fields.

Based on our recent paper [arXiv:2206.12176 (2022)], we propose a scalable heteronuclear architecture of parallel implementation of CNOT gates in arrays of alkali-metal neutral atoms for quantum information processing. We considered a scheme where we perform CNOT gates in a parallel manner within the array, while they are performed sequentially between the pairs of neighboring qubits by coherently transporting an array of atoms of one atomic species (ancilla qubits) using an array of mobile optical dipole traps generated by a 2D acousto-optic deflector (AOD). The atoms of the second atomic species (data qubits) are kept in the array of static optical dipole traps generated by spatial light modulator (SLM). The moving ancillas remain in the superposition of their logical ground states without loss of coherence, while their transportation paths avoid overlaps with the spatial positions of data atoms. We numerically optimized the system parameters to achieve the fidelity for parallelly implemented CNOT gates around (mathcal{F} = 95% ) for the experimentally feasible conditions. Our design can be useful implementation of surface codes for quantum error correction. Renyi entropy and mutual information are also investigated to characterize the gate performance.

A quantum algorithm for solving the traveling salesman problem by the quantum phase estimation and quantum search method is considered. An approach is developed that was previously proposed for solving this problem. A quantum register is used to encode the eigenstates of a unitary operator whose phase determines the length of each possible route. The quantum phase estimation algorithm is used to estimate the length of a route. Then, to find the minimum route length, the measured values of length are encoded into the states of the second quantum register, and the search for the optimal route is carried out using a modified Grover algorithm. Numerical simulation of the proposed quantum algorithm is carried out using the Qiskit library for one and two iterations of the modified Grover algorithm.

Background of the electromagnetically induced transparency (EIT) resonance splitting by millimeter-wave radiation was investigated and so were calculated frequencies and amplitudes of radiation transitions between Rydberg states in alkaline earth atoms of IIA group elements, which are necessary for precise measurements of electric field magnitude at millimeter-wave (mmw) frequencies. Numerical values of the frequencies and matrix elements are approximated by asymptotic polynomials and tabulated for dipole transitions between singlet nS, nP, nD, and nF states with large values of principal quantum number n.