Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2408.11542 · Physical Review Research

Quantum gates between distant atoms mediated by a Rydberg excitation antiferromagnet

Georgios Doultsinos, David Petrosyan

Published Jun 11, 2025• 6 citations
arXivHTMLPDF

Abstract

We present a novel protocol for implementing quantum gates between distant atomic qubits connected by an array of neutral atoms that play the role of a quantum bus. The protocol is based on adiabatically transferring the atoms in the array to an antiferromagnetic-like state of Rydberg excitations using chirped laser pulses. Upon exciting and deexciting the atoms in the array under the blockage of nearest neighbors, depending on the state of the two qubits, the system acquires a conditional geometric π -phase, while the dynamical phase cancels exactly, even when the atomic positions are disordered but nearly frozen in time, which requires sufficiently low temperatures. With experimentally relevant parameters, using smooth pulses minimizing the Rydberg-state decay and nonadiabatic errors, we obtain the gate times of 2– 3 µ s and gate fidelities of 0.99–0.98 for a pair of atoms separated by L = 20 – 30 µ m and connected by a quantum bus of several (three to six) atoms. Optimizing the pulses, we can obtain faster gates exhibiting even better fidelities than those with smooth adiabatic pulses.

DOI
10.1103/physrevresearch.7.023246

Related papers

Multi-qubit Rydberg gates between distant atoms

Antonis Delakouras, Georgios Doultsinos, David Petrosyan

We propose an efficient protocol to realize multi-qubit gates in arrays of neutral atoms. The atoms encode qubits in the long-lived hyperfine sublevels of the ground electronic state. To realize the gate, we apply a global laser pulse to transfer the atoms to a Rydberg state with strong blockade interaction that suppresses simultaneous excitation of neighboring atoms arranged in a star-graph configuration. The number of Rydberg excitations, and thereby the parity of the resulting state, depends on the multiqubit input state. Upon changing the sign of the interaction and de-exciting the atoms with an identical laser pulse, the system acquires a geometric phase that depends only on the parity of the excited state, while the dynamical phase is completely canceled. Using single qubit rotations, this transformation can be converted to the C k Z or C k NOT quantum gate for k + 1 atoms. We also present extensions of the scheme to implement quantum gates between distant atomic qubits connected by a quantum bus consisting of a chain of atoms.

arXiv:2507.16602•Quantum•Jan 28, 2026•3 citations

Two-qubit entangling gates between distant atomic qubits in a lattice

Alexandre Cesa, John Martin

Arrays of qubits encoded in the ground-state manifold of neutral atoms trapped in optical (or magnetic) lattices appear to be a promising platform for the realization of a scalable quantum computer. Two-qubit conditional gates between nearest-neighbor qubits in the array can be implemented by exploiting the Rydberg blockade mechanism, as was shown by D. Jaksch et al. [Phys. Rev. Lett. 85, 2208 (2000)]. However, the energy shift due to dipole-dipole interactions causing the blockade falls off rapidly with the interatomic distance, and protocols based on direct Rydberg blockade typically fail to operate between atoms separated by more than one lattice site. In this work, we propose an extension of the protocol of Jaksch et al. for controlled-$Z$ and controlled-not gates which works in the general case where the qubits are not nearest neighbors in the array. Our proposal relies on the Rydberg excitation hopping along a chain of ancilla noncoding atoms connecting the qubits on which the gate is to be applied. The dependence of the gate fidelity on the number of ancilla atoms, the blockade strength, and the decay rates of the Rydberg states is investigated. A comparison between our implementation of a distant controlled-not gate and one based on a sequence of nearest-neighbor two-qubit gates is also provided.

arXiv:1703.01767•Physical Review A•May 16, 2017•12 citations

Fast Quantum Gates for Neutral Atoms Separated by a Few Tens of Micrometers

Matteo Bergonzoni, Rosario Roberto Riso, Guido Pupillo

We present a theoretical scheme for a family of fast and high-fidelity two-qubit iSWAP gates between neutral atoms separated by more than 20 um, enabled by resonant dipole-dipole spin-exchange interactions between Rydberg states. The protocol harnesses coherent excitation-exchange-deexcitation dynamics between the qubit and the Rydberg states within a single and smooth laser pulse, in the presence of strong dipole-dipole interactions. We utilize optimal control methods to achieve theoretical gate fidelities and durations comparable to blockade-based gates in the presence of relevant noise, while extending the effective interaction range by an order of magnitude. This enables entanglement well beyond the blockade radius, offering a route toward fast, high-connectivity quantum processors.

quant-pharXiv:2511.20437•Physical Review Research•Nov 26, 2025•1 citation

Distant two-qubit gates in atomic array with Rydberg interaction using geometric quantum control

Ze-Rui He, Zhao-Xin Fu, Jia-Hao Liang +8 more

Abstract Connectivity between qubits plays an irreplaceable role in quantum computation. An urgent task of quantum computation based on atomic arrays is to generate effective coupling between two distant qubits, thereby enhancing connectivity. In this paper, we investigate the realization of two-qubit gates utilizing buffer-atomic configuration, where the non-coding atoms serve as quantum buses to connect the computational qubits. Geometric control is achieved through globally-shined laser pulses in the Rydberg blockade region. It is found that acceleration based on shortcut to adiabaticity can be realized by reshaping the original control waveforms. The proposed distant two-qubit gate demonstrates robustness against systematic errors and random noise. Further numerical simulations indicate that high-fidelity control is maintained even when considering next-nearest-neighbor coupling among the atoms. Thus, our proposal provides a fast and experimentally feasible method for realizing distant two-qubit gates in atomic arrays, which may contribute to improving the scalability of quantum computations.

Quantum Frontiers•Dec 3, 2024•1 citation

Quantum computation using dark states in a Rydberg atom array

Sinchan Snigdha Rej, Bimalendu Deb

Abstract Multi-qubit quantum gates are the most important building blocks for quantum computation. In this article, we propose a scheme for realizing the Toffoli gate in a linear neutral atom array. Two ground-state hyperfine levels of the atoms are considered as qubit states. Our method relies on the strong and long-range interactions between atoms due to Rydberg excitations and the occurrence of dark states in the target qubit, with both control and target qubits being individually addressed with laser pulses. Our gate protocol enables precise control over the quantum states of individual qubits, effectively suppressing undesirable transitions to ensure high-fidelity gate performance. We also implement two-atom Rydberg antiblockade mechanism to avoid any unwanted population blockage in the control atoms to get the best fidelity. At zero temperature, the gate fidelity is estimated to be about 99.16% for realistic laser power omitting the motional state of the atoms when the interatomic distance ( l ) 6.55 μ m. We construct a C n NOT gate with n > 2 in a 2D atomic array by exploiting the n -atom Rydberg antiblockade (RAB) mechanism, which allows n atoms within the blockade radius to be simultaneously excited to the Rydberg states. In particular, we simulate C 3 NOT gate with about 98.37 % fidelity. We further analyze the gate error by decreasing the interatomic distance and find that gate fidelity improves more rapidly for larger n with increased interaction potential. We find that more than 99 % fidelity can be achieved for C 3 NOT gate for l < 6.2 μ m, implying that our proposed scheme promising and reliable for multi-qubit controlled NOT gates. For a finite temperature ( ∼ 30 μ K), including the Doppler dephasing, we simulate our gates to achieve 98.90% and 98.54 % fidelity for the Toffoli gate and C 3

Journal of Physics B Atomic Molecular and Optical Physics•May 27, 2026•1 citation

High-fidelity non-adiabatic dark state gates for neutral atoms

Nader Mostaan, Kapil Goswami, Peter Schmelcher +1 more

Rydberg blockade gates are the most experimentally mature entangling operations in neutral-atom quantum processors, combining fast gate times with simple control, but their performance degrades at larger interatomic separations and remains sensitive to motional and technical noise. Non-blockade gate schemes, such as dark-state and geometric protocols, offer complementary robustness but typically rely on complex and experimentally demanding control. Here we show that quantum optimal control enables non-blockade gate schemes to be implemented using the experimentally established pulse-shaping techniques developed for blockade-based gates. Focusing on the dark-state gate, we construct non-adiabatic implementations that preserve the intrinsic robustness of adiabatic dark-state protocols while achieving gate times comparable to time-optimal blockade gates using only smooth, experimentally feasible pulses. The resulting gates exhibit enhanced resilience to motional coupling, laser noise, and interaction inhomogeneity, particularly near and beyond the blockade radius. This work establishes a practical route to fast, robust two-qubit gates without increased experimental complexity.

quant-pharXiv:2602.13885•Feb 17, 2026•0 citations
We present a novel protocol for implementing quantum gates between distant atomic qubits connected by an array of neutral atoms that play the role of a quantum bus. The protocol is based on adiabatically transferring the atoms in the array to an antiferromagnetic-like state of Rydberg excitations using chirped laser pulses. Upon exciting and deexciting the atoms in the array under the blockage of nearest neighbors, depending on the state of the two qubits, the system acquires a conditional geometric π -phase, while the dynamical phase cancels exactly, even when the atomic positions are disordered but nearly frozen in time, which requires sufficiently low temperatures. With experimentally relevant parameters, using smooth pulses minimizing the Rydberg-state decay and nonadiabatic errors, we obtain the gate times of 2– 3 µ s and gate fidelities of 0.99–0.98 for a pair of atoms separated by L = 20 – 30 µ m and connected by a quantum bus of several (three to six) atoms. Optimizing the pulses, we can obtain faster gates exhibiting even better fidelities than those with smooth adiabatic pulses.
We propose an efficient protocol to realize multi-qubit gates in arrays of neutral atoms. The atoms encode qubits in the long-lived hyperfine sublevels of the ground electronic state. To realize the gate, we apply a global laser pulse to transfer the atoms to a Rydberg state with strong blockade interaction that suppresses simultaneous excitation of neighboring atoms arranged in a star-graph configuration. The number of Rydberg excitations, and thereby the parity of the resulting state, depends on the multiqubit input state. Upon changing the sign of the interaction and de-exciting the atoms with an identical laser pulse, the system acquires a geometric phase that depends only on the parity of the excited state, while the dynamical phase is completely canceled. Using single qubit rotations, this transformation can be converted to the C k Z or C k NOT quantum gate for k + 1 atoms. We also present extensions of the scheme to implement quantum gates between distant atomic qubits connected by a quantum bus consisting of a chain of atoms.
Arrays of qubits encoded in the ground-state manifold of neutral atoms trapped in optical (or magnetic) lattices appear to be a promising platform for the realization of a scalable quantum computer. Two-qubit conditional gates between nearest-neighbor qubits in the array can be implemented by exploiting the Rydberg blockade mechanism, as was shown by D. Jaksch et al. [Phys. Rev. Lett. 85, 2208 (2000)]. However, the energy shift due to dipole-dipole interactions causing the blockade falls off rapidly with the interatomic distance, and protocols based on direct Rydberg blockade typically fail to operate between atoms separated by more than one lattice site. In this work, we propose an extension of the protocol of Jaksch et al. for controlled-ZZZ and controlled-not gates which works in the general case where the qubits are not nearest neighbors in the array. Our proposal relies on the Rydberg excitation hopping along a chain of ancilla noncoding atoms connecting the qubits on which the gate is to be applied. The dependence of the gate fidelity on the number of ancilla atoms, the blockade strength, and the decay rates of the Rydberg states is investigated. A comparison between our implementation of a distant controlled-not gate and one based on a sequence of nearest-neighbor two-qubit gates is also provided.
We present a theoretical scheme for a family of fast and high-fidelity two-qubit iSWAP gates between neutral atoms separated by more than 20 um, enabled by resonant dipole-dipole spin-exchange interactions between Rydberg states. The protocol harnesses coherent excitation-exchange-deexcitation dynamics between the qubit and the Rydberg states within a single and smooth laser pulse, in the presence of strong dipole-dipole interactions. We utilize optimal control methods to achieve theoretical gate fidelities and durations comparable to blockade-based gates in the presence of relevant noise, while extending the effective interaction range by an order of magnitude. This enables entanglement well beyond the blockade radius, offering a route toward fast, high-connectivity quantum processors.
Abstract Connectivity between qubits plays an irreplaceable role in quantum computation. An urgent task of quantum computation based on atomic arrays is to generate effective coupling between two distant qubits, thereby enhancing connectivity. In this paper, we investigate the realization of two-qubit gates utilizing buffer-atomic configuration, where the non-coding atoms serve as quantum buses to connect the computational qubits. Geometric control is achieved through globally-shined laser pulses in the Rydberg blockade region. It is found that acceleration based on shortcut to adiabaticity can be realized by reshaping the original control waveforms. The proposed distant two-qubit gate demonstrates robustness against systematic errors and random noise. Further numerical simulations indicate that high-fidelity control is maintained even when considering next-nearest-neighbor coupling among the atoms. Thus, our proposal provides a fast and experimentally feasible method for realizing distant two-qubit gates in atomic arrays, which may contribute to improving the scalability of quantum computations.
Abstract Multi-qubit quantum gates are the most important building blocks for quantum computation. In this article, we propose a scheme for realizing the Toffoli gate in a linear neutral atom array. Two ground-state hyperfine levels of the atoms are considered as qubit states. Our method relies on the strong and long-range interactions between atoms due to Rydberg excitations and the occurrence of dark states in the target qubit, with both control and target qubits being individually addressed with laser pulses. Our gate protocol enables precise control over the quantum states of individual qubits, effectively suppressing undesirable transitions to ensure high-fidelity gate performance. We also implement two-atom Rydberg antiblockade mechanism to avoid any unwanted population blockage in the control atoms to get the best fidelity. At zero temperature, the gate fidelity is estimated to be about 99.16% for realistic laser power omitting the motional state of the atoms when the interatomic distance ( l ) 6.55 μ m. We construct a C n NOT gate with n > 2 in a 2D atomic array by exploiting the n -atom Rydberg antiblockade (RAB) mechanism, which allows n atoms within the blockade radius to be simultaneously excited to the Rydberg states. In particular, we simulate C 3 NOT gate with about 98.37 % fidelity. We further analyze the gate error by decreasing the interatomic distance and find that gate fidelity improves more rapidly for larger n with increased interaction potential. We find that more than 99 % fidelity can be achieved for C 3 NOT gate for l < 6.2 μ m, implying that our proposed scheme promising and reliable for multi-qubit controlled NOT gates. For a finite temperature ( ∼ 30 μ K), including the Doppler dephasing, we simulate our gates to achieve 98.90% and 98.54 % fidelity for the Toffoli gate and C 3
Rydberg blockade gates are the most experimentally mature entangling operations in neutral-atom quantum processors, combining fast gate times with simple control, but their performance degrades at larger interatomic separations and remains sensitive to motional and technical noise. Non-blockade gate schemes, such as dark-state and geometric protocols, offer complementary robustness but typically rely on complex and experimentally demanding control. Here we show that quantum optimal control enables non-blockade gate schemes to be implemented using the experimentally established pulse-shaping techniques developed for blockade-based gates. Focusing on the dark-state gate, we construct non-adiabatic implementations that preserve the intrinsic robustness of adiabatic dark-state protocols while achieving gate times comparable to time-optimal blockade gates using only smooth, experimentally feasible pulses. The resulting gates exhibit enhanced resilience to motional coupling, laser noise, and interaction inhomogeneity, particularly near and beyond the blockade radius. This work establishes a practical route to fast, robust two-qubit gates without increased experimental complexity.