Dynamical generation of chiral $W$ and Greenberger-Horne-Zeilinger states in laser-controlled Rydberg-atom trimers

Abstract

Owing to the significantly improved scalability of optically-trapped neutral-atom systems, which makes the prospect of large-scale quantum computing increasingly realistic, extensive efforts have been devoted in recent years to quantum-state engineering in Rydberg-atom ensembles. Motivated by this spate of research activity, we investigate the problem of engineering generalized ("twisted") W states, as well as Greenberger-Horne-Zeilinger (GHZ) states, in the Rydberg-blockade regime of a neutral-atom system. We assume that each atom in the envisioned system initially resides in its ground state and is subject to several external laser pulses that are close to being resonant with the same internal atomic transition. In particular, in the special case of a three-atom system (Rydberg-atom trimer) we determine configurations of field alignments and atomic positions that enable the realization of chiral W states -a special type of twisted three-qubit W states of interest for implementing noiseless-subsystem qubit encoding. In addition, we also address the problem of interconversion between twisted W and GHZ states in the same three-atom system, thus generalizing our recent work that involves ordinary W states [T. Haase et al., Phys. Rev. A 103, 032427 (2021)]. Compared to this previous study, our principal finding is that starting from twisted W states is equivalent to renormalizing downwards the relevant Rabi frequencies. Consequently, a larger laser pulse energy is required to carry out the desired state conversion within the same time frame.

Quantum-brachistochrone approach to the conversion from $W$ to Greenberger-Horne-Zeilinger states for Rydberg-atom qubits

“…In particular, maximally-entangled multiqubit states of W - [2] and GHZ [3] type are of both conceptual and practical importance in the realm of quantum-information processing (QIP) [4]. Owing to their already proven usefulness in QIP [5,6], a large number of schemes for the preparation of W [7][8][9][10][11][12][13][14][15] and GHZ states [16][17][18][19][20][21] in various physical platforms have been proposed in recent years. Among those platforms, one of the most promising ones from the standpoint of large-scale quantum computing and analog quantum simulation, is based on ensembles of neutral atoms in Rydberg states [22][23][24][25].…”

Interconversion of $W$ and Greenberger-Horne-Zeilinger states for Ising-coupled qubits with transverse global control

“…In the realm of atomic systems, irreversible conversions of W -into GHZ states were first proposed [35,36]. More recently, the deterministic interconversion between the two states in a system of three Rydberg-atom-based qubits [37,38] subject to four external laser pulses was extensively studied [39][40][41][42].…”

Coherent atom transport via enhanced shortcuts to adiabaticity: Double-well optical lattice

“…Fast, nearly lossless, transport of cold neutral atoms [1][2][3][4][5][6][7][8][9][10] is of paramount interest for emerging quantum-technology applications [11] such as quantum sensing and interferometry [12,13]. It is also a prerequsite for neutral-atom quantum computing [14][15][16], as well as analog simulation [15] and quantum-state engineering in ensembles of Rydberg atoms [17][18][19]. In particular, single-atom transport processes [20] enabled by moving the confining optical trap -either an optical lattice or a tweezer [21][22][23] -have attracted considerable attention quite recently, both theoretically [8,10,24,25] and experimentally [10,26].…”