Efficient three-qubit gates with giant atoms

• URL: http://arxiv.org/abs/2510.04545v1
• Date: Mon, 06 Oct 2025 07:22:16 GMT
• Title: Efficient three-qubit gates with giant atoms
• Authors: Guangze Chen, Anton Frisk Kockum,
• Abstract summary: We propose and analyze the implementation of fast, high-fidelity three-qubit gates using giant atoms and a waveguide.<n>We show that fidelities exceeding 99.5% are achievable with current experimental parameters in superconducting circuits.<n>Our results position giant-atom systems as a promising platform for entangled-state preparation and low-depth quantum circuit design in near-term quantum computers and quantum simulators.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Three-qubit gates are highly beneficial operations in quantum computing, enabling compact implementations of quantum algorithms and efficient generation of multipartite entangled states. However, realizing such gates with high fidelity remains challenging due to crosstalk, complex control requirements, and the overhead of parametric or tunable couplers. In this work, we propose and analyze the implementation of fast, high-fidelity three-qubit gates using giant atoms--artificial atoms coupled to a waveguide at multiple spatially separated points. By leveraging interference effects intrinsic to the giant-atom architecture, we demonstrate that native three-qubit gates, such as the controlled-CZ-SWAP (CCZS) and the dual-iSWAP (DIV), can be realized through simple frequency tuning, without the need for complex pulse shaping or additional hardware. We evaluate gate performance under realistic decoherence and show that fidelities exceeding 99.5% are achievable with current experimental parameters in superconducting circuits. As an application, we present a scalable protocol for preparing three- and five-qubit GHZ states using minimal gate depth, achieving high state fidelity within sub-300ns timescales. Our results position giant-atom systems as a promising platform for entangled-state preparation and low-depth quantum circuit design in near-term quantum computers and quantum simulators.

Related papers

• Parity Cross-Resonance: A Multiqubit Gate [5.6995215414894735]
  We present a native three-qubit entangling gate that exploits engineered interactions to realize control-control-target and control-target-target operations.<n>We show it can be utilized in several ways, for example, in GHZ triplet state preparation.
  arXiv  Detail & Related papers  (2025-08-14T16:26:32Z)
• Scalable quantum simulator with an extended gate set in giant atoms [0.0]
  We propose a scalable quantum simulator with an extended gate set based on giant-atom three-level systems.<n>By leveraging this tunability, our setup supports both CZ and iSWAP gates through simple frequency adjustments.<n>As a demonstration, we showcase the simulation of spin dynamics in dissipative Heisenberg XXZ spin chains.
  arXiv  Detail & Related papers  (2025-03-06T15:22:37Z)
• Direct Implementation of High-Fidelity Three-Qubit Gates for Superconducting Processor with Tunable Couplers [18.682049956714156]
  Three-qubit gates can be constructed using combinations of single-qubit and two-qubit gates, making their independent realization unnecessary.<n>We propose and experimentally demonstrate a high-fidelity scheme for implementing a three-qubit controlled-controlled-Z (CCZ) gate in a flip-chip superconducting quantum processor with tunable couplers.
  arXiv  Detail & Related papers  (2025-01-30T12:57:57Z)
• Realizing Scalable Conditional Operations through Auxiliary Energy Levels [12.939689760182203]
  We propose a transition composite gate scheme based on transition pathway engineering.<n>We demonstrate the controlled-unitary (CU) family and its applications.
  arXiv  Detail & Related papers  (2024-07-09T09:01:04Z)
• Quantum Compiling with Reinforcement Learning on a Superconducting Processor [55.135709564322624]
  We develop a reinforcement learning-based quantum compiler for a superconducting processor. We demonstrate its capability of discovering novel and hardware-amenable circuits with short lengths. Our study exemplifies the codesign of the software with hardware for efficient quantum compilation.
  arXiv  Detail & Related papers  (2024-06-18T01:49:48Z)
• QuantumSEA: In-Time Sparse Exploration for Noise Adaptive Quantum Circuits [82.50620782471485]
  QuantumSEA is an in-time sparse exploration for noise-adaptive quantum circuits. It aims to achieve two key objectives: (1) implicit circuits capacity during training and (2) noise robustness. Our method establishes state-of-the-art results with only half the number of quantum gates and 2x time saving of circuit executions.
  arXiv  Detail & Related papers  (2024-01-10T22:33:00Z)
• High-fidelity parallel entangling gates on a neutral atom quantum computer [41.74498230885008]
  We report the realization of two-qubit entangling gates with 99.5% fidelity on up to 60 atoms in parallel. These advances lay the groundwork for large-scale implementation of quantum algorithms, error-corrected circuits, and digital simulations.
  arXiv  Detail & Related papers  (2023-04-11T18:00:04Z)
• Direct pulse-level compilation of arbitrary quantum logic gates on superconducting qutrits [36.30869856057226]
  We demonstrate any arbitrary qubit and qutrit gate can be realized with high-fidelity, which can significantly reduce the length of a gate sequence. We show that optimal control gates are robust to drift for at least three hours and that the same calibration parameters can be used for all implemented gates.
  arXiv  Detail & Related papers  (2023-03-07T22:15:43Z)
• Optimal quantum control via genetic algorithms for quantum state engineering in driven-resonator mediated networks [68.8204255655161]
  We employ a machine learning-enabled approach to quantum state engineering based on evolutionary algorithms. We consider a network of qubits -- encoded in the states of artificial atoms with no direct coupling -- interacting via a common single-mode driven microwave resonator. We observe high quantum fidelities and resilience to noise, despite the algorithm being trained in the ideal noise-free setting.
  arXiv  Detail & Related papers  (2022-06-29T14:34:00Z)
• High-fidelity three-qubit iToffoli gate for fixed-frequency superconducting qubits [0.0]
  We introduce a high-fidelity iToffoli gate based on two-qubit interactions, the so-called cross-resonance effect. The iToffoli gate is implemented by simultaneously applying microwave pulses to a linear chain of three qubits, revealing a process fidelity as high as 98.26(2)%. We numerically show that our gate scheme can produce additional three-qubit gates which provide more efficient gate synthesis than the Toffoli and iToffoli gates.
  arXiv  Detail & Related papers  (2021-08-23T17:00:16Z)
• Realization of arbitrary doubly-controlled quantum phase gates [62.997667081978825]
  We introduce a high-fidelity gate set inspired by a proposal for near-term quantum advantage in optimization problems. By orchestrating coherent, multi-level control over three transmon qutrits, we synthesize a family of deterministic, continuous-angle quantum phase gates acting in the natural three-qubit computational basis.
  arXiv  Detail & Related papers  (2021-08-03T17:49:09Z)
• Improving the Performance of Deep Quantum Optimization Algorithms with Continuous Gate Sets [47.00474212574662]
  Variational quantum algorithms are believed to be promising for solving computationally hard problems. In this paper, we experimentally investigate the circuit-depth-dependent performance of QAOA applied to exact-cover problem instances. Our results demonstrate that the use of continuous gate sets may be a key component in extending the impact of near-term quantum computers.
  arXiv  Detail & Related papers  (2020-05-11T17:20:51Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.