arXiv subjects

Y. Q. Ji

Publications and source records attributed to Y. Q. Ji.

8 recordsLinked to original sources

arXiv2026

Giant-atom-mediated photon blockade

Photon blockade is a phenomenon where the presence of system nonlinearity causes the output to consist of single photons, which has been extensively studied in point atom systems, but it is barely explored in giant atom ones. In this paper, we propose giant atom-mediated photon blockade scheme based on two cavities and three cavities systems with driving field applied to the first cavity. We show that simultaneous unconventional photon blockades (UPBs) can not occur in the point atom system (the atom coupling only to the leftmost cavity) due to there always existing a cavity to have a single path. In contrast, the spatially extended nature of giant atom enables coupling to multiple cavities and allows for the introduction of a phase and coupling strength. Consequently, simultaneous UPBs in multiple cavities can be obtained due to the multipath destructive interference. Moreover, by manipulating the detuning, we observe simultaneous conventional photon blockades (CPBs) in multiple cavities. Finally, we study simultaneous two-photon blockades (2PBs) in point atom multiple cavities system.

quant-ph↗

arXiv2026

On the Power Set of Quasinilpotent Operators in Banach Spaces

For a quasinilpotent operator $T$ on a Banach space $X$, Douglas and Yang defined $k_{x}=\limsup\limits_{λ\rightarrow 0}\frac{\ln\|(λ-T)^{-1}x\|}{\ln\|(λ-T)^{-1}\|}$ for each non-zero vector $x$, and called $Λ(T)=\{k_x:x\neq 0\}$ the power set of $T$. In this paper, we prove that $Λ(T)$ always contains $1$ for every quasinilpotent operator $T$ on $X$. Moreover, we introduce the concept of a Banach space $X$ having uniform multiplicity infinity and prove that some classical Banach spaces possess this property. As an application, we show that if $σ\subset [0,1]$ is right closed and contains $1$, then there exists a quasinilpotent operator $T$ on a class of Banach spaces with uniform multiplicity infinity such that $Λ(T)=σ$.

math.FA↗

arXiv2024

Deterministic interconversion of GHZ state and KLM state via Lie-transform-based pulse design in Rydberg atoms

Conversion between different types of entangled states is an interesting problem in quantum mechanics. But research on the conversion between Greenberger-Horne-Zeilinger (GHZ) state and Knill-Laflamme-Milburn (KLM) state in atomic system is absent. In this paper, we propose a scheme to realize the interconversion (one-step) between GHZ state and KLM state with Rydberg atoms. By utilizing Rydberg-mediated interactions, we simplify the system. By combining Lie-transform-based pulse design, the evolution path is built up to realize interconversion of GHZ state and KLM state. The numerical simulation result shows that the present scheme is robust against decoherence and operational imperfection, the analysis shows that the scheme is feasible with current experimental technology.

quant-ph↗

arXiv2017

Ground-state blockade of Rydberg atoms and application in entanglement generation

We propose a mechanism of ground-state blockade between two $N$-type Rydberg atoms in virtue of Rydberg-antiblockade effect and Raman transition. Inspired by the quantum Zeno effect, the strong Rydberg antiblockade interaction plays a role in frequently measuring one ground state of two, leading to a blockade effect for double occupation of the corresponding quantum state. By encoding the logic qubits into the ground states, we efficiently avoid the spontaneous emission of the excited Rydberg state, and maintain the nonlinear Rydberg-Rydberg interaction at the same time. As applications, we discuss in detail the feasibility of preparing two-atom and three-atom entanglement with ground-state blockade in closed system and open system, respectively, which shows that a high fidelity of entangled state can be obtained with current experimental parameters.

quant-ph↗

arXiv2017

Entangled state fusion with Rydberg atoms

We propose a scheme for preparation of large-scale entangled $GHZ$ states and $W$ states with neutral Rydberg atoms. The scheme mainly depends on Rydberg antiblockade effect, i.e., as the Rydberg-Rydberg-interaction (RRI) strength and the detuning between the atom transition frequency and the classical laser frequency satisfies some certain conditions, the effective Rabi oscillation between the two ground states and the two excitation Rydberg states would be generated. The prominent advantage is that both two-multiparticle $GHZ$ states and two-multiparticle $W$ states can be fused in this model, especially the success probability for fusion of $GHZ$ states can reach unit. In addition, the imperfections induced by the spontaneous emission is also discussed through numerical simulation.

quant-ph↗

arXiv2017

Fusing atomic $W$ states via quantum Zeno dynamics

We propose a scheme for preparation of large-scale entangled $W$ states based on the fusion mechanism via quantum Zeno dynamics. By sending two atoms belonging to an $n$-atom $W$ state and an $m$-atom $W$ state, respectively, into a vacuum cavity (or two separate cavities), we may obtain a ($n+m-2$)-atom $W$ state via detecting the two-atom state after interaction. The present scheme is robust against both spontaneous emission of atoms and decay of cavity, and the feasibility analysis indicates that it can also be realized in experiment.

quant-ph↗

arXiv2017

Enhanced exciton transmission by quantum-jump-based feedback

With rotating-wave approximation (RWA), we show in this paper that exciton transmission in a one-dimensional two-level molecule chain embedded in a cavity can be enhanced or suppressed by strong cavity-chain couplings. This exciton transmission is closely related to the number of molecules and the distribution of molecular exciton energy. In addition, we propose a proposal to enhance the exciton transmission by quantum-jump-based feedback. These results may find applications in experiments of exciton transmission in organic materials.

quant-ph↗

arXiv2017

Conversion of entangled states with nitrogen-vacancy centers coupled to microtoroidal resonators

We propose efficient schemes for converting three-photon, four-photon and five-photon GHZ state to a $W$ state or Dicke state, respectively with the nitrogen-vacancy (N-V) centers via single-photon input-output process and cross-Kerr nonlinearities. The total success probability can be improved by iterating the conversion process for the case of three-photon and five-photon while it does not require iteration for converting four-photon GHZ state to a $W$ state. The analysis of feasibility shows that our scheme is feasible for current experimental technology.

quant-ph↗