Efficient direct quantum state tomography using fan-out couplings

• URL: http://arxiv.org/abs/2604.04454v1
• Date: Mon, 06 Apr 2026 06:02:27 GMT
• Title: Efficient direct quantum state tomography using fan-out couplings
• Abstract summary: We introduce a direct quantum state tomography scheme combining strong-measurement estimation with a fan-out coupling architecture.<n>We experimentally validate the scheme on a superconducting quantum processor via the IBM Quantum Platform.
• Score: 0.2796197251957245
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Characterizing quantum states is essential for validating quantum devices, yet conventional quantum state tomography becomes prohibitively expensive as system size grows. Direct tomography offers a distinct route by enabling selective access to individual complex density-matrix elements, with a particular advantage for sparse target states and some verification tasks. Here we introduce a direct quantum state tomography scheme combining strong-measurement estimation with a fan-out coupling architecture. It enables mutually commuting interactions between system qubits and a single meter qubit, thereby achieving constant circuit depth, independent of system size. Notably, the involutory fan-out coupling reduces to the identity under repetition, enabling straightforward noise scaling for quantum error mitigation. We experimentally validate the scheme on a superconducting quantum processor via the IBM Quantum Platform, demonstrating four-qubit state reconstruction and single-circuit GHZ-state fidelity estimation up to 20 qubits with error mitigation. Consistent results with standard tomography and improved efficiency establish our scheme as a promising approach to reconstructing full quantum states and scalable verification tasks.

Related papers

• Rigorous characterization of continuous-variable quantum states via optical parametric amplifiers [0.0]
  We introduce an integrated framework for loss-tolerant characterization and certification.<n>We develop a certification framework that directly quantifies non-Gaussianity via stellar-rank witnesses and Wigner negativity.<n>By unifying loss-tolerant measurements, state tomography, and non-state certification within a single experimentally accessible framework, our approach provides a practical pathway toward verifying increasingly complex states.
  arXiv  Detail & Related papers  (2026-07-19T01:22:27Z)
• Quantum Machine Learning for State Tomography Using Classical Data [0.0]
  Reconstructing quantum states from measurement data represents a formidable challenge in quantum information science.<n>Recent studies have explored quantum machine learning (QML) for quantum state tomography (QST)<n>We present a QML-based tomography protocol that operates entirely on classical measurement data and is fully executable on noisy intermediate-scale quantum (NISQ) devices.
  arXiv  Detail & Related papers  (2025-07-01T23:42:19Z)
• Experimental verification of Threshold Quantum State Tomography on a fully-reconfigurable photonic integrated circuit [0.0]
  We show experimentally the application of an approach, called threshold quantum state tomography, in an advanced hybrid photonic platform.<n>This approach does not require a priori knowledge on the state, and selects only the informative projectors starting from the measurement of the density matrix diagonal.<n>We show the effectiveness of this approach in a photonic platform, showing that a consistent reduction in the number of measurement is obtained while reconstructing relevant states for quantum protocols, with only very limited loss of information.
  arXiv  Detail & Related papers  (2025-04-07T13:47:41Z)
• Realization of Constant-Depth Fan-Out with Real-Time Feedforward on a Superconducting Quantum Processor [33.096693427147535]
  We demonstrate a quantum fan-out gate with real-time feedforward on up to four output qubits using a superconducting quantum processor. Our work highlights the potential of mid-circuit measurements combined with real-time conditional operations to improve the efficiency of complex quantum algorithms.
  arXiv  Detail & Related papers  (2024-09-11T03:40:24Z)
• Mixed-Dimensional Qudit State Preparation Using Edge-Weighted Decision Diagrams [3.393749500700096]
  Quantum computers have the potential to solve intractable problems. One key element to exploiting this potential is the capability to efficiently prepare quantum states for multi-valued, or qudit, systems. In this paper, we investigate quantum state preparation with a focus on mixed-dimensional systems.
  arXiv  Detail & Related papers  (2024-06-05T18:00:01Z)
• A Quantum-Classical Collaborative Training Architecture Based on Quantum State Fidelity [50.387179833629254]
  We introduce a collaborative classical-quantum architecture called co-TenQu. Co-TenQu enhances a classical deep neural network by up to 41.72% in a fair setting. It outperforms other quantum-based methods by up to 1.9 times and achieves similar accuracy while utilizing 70.59% fewer qubits.
  arXiv  Detail & Related papers  (2024-02-23T14:09:41Z)
• Mitigating Errors on Superconducting Quantum Processors through Fuzzy Clustering [38.02852247910155]
  A new Quantum Error Mitigation (QEM) technique uses Fuzzy C-Means clustering to specifically identify measurement error patterns. We report a proof-of-principle validation of the technique on a 2-qubit register, obtained as a subset of a real NISQ 5-qubit superconducting quantum processor. We demonstrate that the FCM-based QEM technique allows for reasonable improvement of the expectation values of single- and two-qubit gates based quantum circuits.
  arXiv  Detail & Related papers  (2024-02-02T14:02:45Z)
• Enhanced quantum state transfer: Circumventing quantum chaotic behavior [35.74056021340496]
  We show how to transfer few-particle quantum states in a two-dimensional quantum network. Our approach paves the way to short-distance quantum communication for connecting distributed quantum processors or registers.
  arXiv  Detail & Related papers  (2024-02-01T19:00:03Z)
• Reliable Quantum Communications based on Asymmetry in Distillation and Coding [35.693513369212646]
  We address the problem of reliable provision of entangled qubits in quantum computing schemes. We combine indirect transmission based on teleportation and distillation; (2) direct transmission, based on quantum error correction (QEC) Our results show that ad-hoc asymmetric codes give, compared to conventional QEC, a performance boost and codeword size reduction both in a single link and in a quantum network scenario.
  arXiv  Detail & Related papers  (2023-05-01T17:13:23Z)
• Quantum process tomography of continuous-variable gates using coherent states [49.299443295581064]
  We demonstrate the use of coherent-state quantum process tomography (csQPT) for a bosonic-mode superconducting circuit. We show results for this method by characterizing a logical quantum gate constructed using displacement and SNAP operations on an encoded qubit.
  arXiv  Detail & Related papers  (2023-03-02T18:08:08Z)
• Efficient Bipartite Entanglement Detection Scheme with a Quantum Adversarial Solver [89.80359585967642]
  Proposal reformulates the bipartite entanglement detection as a two-player zero-sum game completed by parameterized quantum circuits. We experimentally implement our protocol on a linear optical network and exhibit its effectiveness to accomplish the bipartite entanglement detection for 5-qubit quantum pure states and 2-qubit quantum mixed states.
  arXiv  Detail & Related papers  (2022-03-15T09:46:45Z)
• Efficient verification of entangled continuous-variable quantum states with local measurements [0.9825966924601679]
  We establish a systematic framework for verifying entangled continuous-variable quantum states by employing local measurements only. Our protocol is able to achieve the unconditionally high verification efficiency which is quadratically better than quantum tomography.
  arXiv  Detail & Related papers  (2021-03-30T11:59:03Z)
• Loss-tolerant concatenated Bell-state measurement with encoded coherent-state qubits for long-range quantum communication [0.0]
  A coherent-state qubit is a promising candidate for optical quantum information processing. We propose a hardware-efficientd BSM scheme with modified parity encoding. We numerically show that the CBSM scheme achieves a success probability arbitrarily close to unity.
  arXiv  Detail & Related papers  (2021-02-08T09:13:47Z)
• Direct Quantum Communications in the Presence of Realistic Noisy Entanglement [69.25543534545538]
  We propose a novel quantum communication scheme relying on realistic noisy pre-shared entanglement. Our performance analysis shows that the proposed scheme offers competitive QBER, yield, and goodput.
  arXiv  Detail & Related papers  (2020-12-22T13:06:12Z)

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.