arXiv subjects

Tiecheng Wang

Publications and source records attributed to Tiecheng Wang.

3 recordsLinked to original sources

arXiv2026

Robust controlled-Z gate for Rydberg atoms based on level-crossing-free echoing rapid adiabatic passage

We propose a controlled-Z gate scheme for Rydberg atoms based on level-crossing-free echoing rapid adiabatic population transfer. We design antisymmetric Rabi frequency pulses and symmetric detuning pulses, enabling the system to completely avoid level-crossing points throughout the evolution, and the dynamical phase is naturally eliminated by the time-reversal symmetry of the double-pulse sequence. We incorporate dissipative effects through the Lindblad master equation. The numerical simulation yields a two-qubit CZ gate fidelity of 0.9999. When the Rabi-frequency fluctuation is within $\pm 2\%$, and the detuning offset is within $\pm 1\%$, the fidelity can still remain above 0.999. Under the same dissipative model, the three-qubit CCZ gate achieves a fidelity of 0.999. When a single-parameter fluctuation does not exceed $\pm 3\%$, the fidelity is always higher than 0.997. Our scheme requires no laser phase jumps or fast switching operations. The zero-area pulse structure suppresses first-order intensity noise, and the symmetric double-pulse sequence avoids spatially resolved laser switching, making it suitable for parallel gate operations in large-scale neutral-atom arrays.

quant-ph↗

arXiv2026

High-fidelity multiqubit gates with Rydberg atoms via level-crossing-free Rapid adiabatic passage

We propose a rapid adiabatic passage (RAP) scheme based on level-crossing-free pulses for deterministic generation of multiqubit entangled states in Rydberg atom systems. Unlike conventional RAP protocols that rely on level crossings, our approach uses an antisymmetric Rabi frequency and an even-symmetric detuning, enabling robust population transfer without passing through any level crossing. By exploiting the Rydberg blockade effect, the protocol prepares entangled states directly from an initial product state. Specifically, two sequential RAP pulses separated by a pi_g pulse generate two-qubit Bell states, three-qubit W states, four-qubit GHZ states, and six-qubit honeycomb W states. Numerical simulations show that the fidelities exceed 0.9997 for the Bell and three-qubit W states, reach 0.997 for the four-qubit GHZ state, and surpass 0.9995 for the six-qubit honeycomb W state. The scheme demonstrates excellent robustness against pulse parameter fluctuations, with fidelities remaining above 0.99 under +/-5% parameter variations. This work provides a simple, efficient, and robust method for entangled-state preparation in neutral-atom quantum information processing.

quant-ph↗

arXiv2021

Unidirectional weak visibility in band gap and singular scattering in conduction band of one-dimensional parity-time symmetric photonic crystal

We explore the absorption and scattering properties of one dimensional parity-time ($\mathcal{PT}$)-symmetric photonic crystal. In addition to the familiar transmittance and reflectance, we give the definition of the generalized absorptance to include the amplifying effect of the dielectric with negative imaginary part of the permittivity, moreover, we present the mathematical expressions of the transmittance, reflectances and absorptances from both sides of this photonic crystal with N periods in terms of the elements of the transfer matrix of the primitive cell. The complex band structure of this photonic crystal is studied and the corresponding evolutions of the exceptional points, $\mathcal{PT}$-exact phase and $\mathcal{PT}$-broken phase are disclosed. Near the exceptional points, we find some singular behaviors, the transmittance and reflectances from both sides are all greater than one and even all reach large values at the same time, then the corresponding absorptances from both sides are negative. In the band gap, the transmittance is zero, the reflectance form one side can be very large, while the reflectance from the other side is very small, we call this phenomenon unidirectional weak visibility. We believe that these phenomena are very beneficial for the design of the optical devices.

physics.optics↗