Efficient state estimation on quantum processors

• URL: http://arxiv.org/abs/2510.16117v1
• Date: Fri, 17 Oct 2025 18:03:21 GMT
• Title: Efficient state estimation on quantum processors
• Authors: Victor Gonzalez Avella, Abraham Vega Vargas, Tomas Merlo Vergara, Kevin de la Ossa Doria, Jakub Czartowski, Dougal Main, Gabriel Araneda, Aldo Delgado, Dardo Goyeneche,
• Abstract summary: We present two scalable and entanglement-free methods for estimating the collective state of an n-qubit quantum computer.<n>The first method consists of a fixed set of five quantum circuits-regardless of the number of qubits-that avoid the use of entanglement as a measurement resource.<n>The second method requires only 2n+1 circuits, each of which applies a single local gate to one of the n qubits during the measurement stage.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We present two scalable and entanglement-free methods for estimating the collective state of an n-qubit quantum computer. The first method consists of a fixed set of five quantum circuits-regardless of the number of qubits-that avoid the use of entanglement as a measurement resource, relying instead on classical communication between selected pairs of qubits. The second method requires only 2n+1 circuits, each of which applies a single local gate to one of the n qubits during the measurement stage. Unlike traditional estimation methods, our approaches do not require any costly post-processing procedure to estimate a quantum state, enabling scalability to relatively large system sizes. We experimentally compare both methods on freely available IBM quantum processors, and observe how the state estimation varies with increasing number of qubits and shots. We further validated our results by estimating the 4-qubit entangled state of two remote ion-trap quantum processors, demonstrating that the optimized 2n+1 tomographic scheme achieves estimates consistent with standard methods while using exponentially fewer measurements.

Related papers

• State Similarity in Modular Superconducting Quantum Processors with Classical Communications [41.94024259927014]
  We propose a cross-platform fidelity estimation algorithm tailored for modular architectures.<n>We experimentally implement the protocol on modular superconducting quantum processors with up to 6 qubits to verify the similarity of two 11-qubit GHZ states.<n>As a proof of concept, we apply it to a 5-qubit quantum phase learning task using six 3-qubit modules, successfully extracting phase information with just eight training samples.
  arXiv  Detail & Related papers  (2025-06-02T13:27:38Z)
• Operating two exchange-only qubits in parallel [0.3552560736552948]
  We show the parallel operation of two exchange-only qubits, consisting of six quantum dots in a linear arrangement.<n>We also show the first experimental demonstrations of an iSWAP gate and of a charge-locking Pauli spin blockade readout method.
  arXiv  Detail & Related papers  (2025-04-01T21:12:31Z)
• Non-unitary Coupled Cluster Enabled by Mid-circuit Measurements on Quantum Computers [37.69303106863453]
  We propose a state preparation method based on coupled cluster (CC) theory, which is a pillar of quantum chemistry on classical computers. Our approach leads to a reduction of the classical computation overhead, and the number of CNOT and T gates by 28% and 57% on average.
  arXiv  Detail & Related papers  (2024-06-17T14:10:10Z)
• Certifying almost all quantum states with few single-qubit measurements [0.9558392439655012]
  We show that almost all n-qubit target states can be certified from only O(n2) single-qubit measurements. We show that such verified representations can be used to efficiently predict highly non-local properties.
  arXiv  Detail & Related papers  (2024-04-10T18:21:11Z)
• 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)
• Direct tomography of quantum states and processes via weak measurements of Pauli spin operators on an NMR quantum processor [3.818504253546488]
  We present an efficient weak measurement-based scheme for direct quantum state tomography (DQST) and direct quantum process tomography (DQPT) We experimentally implement these weak measurement-based DQST and DQPT protocols and use them to accurately characterize several two-qubit quantum states and single-qubit quantum processes.
  arXiv  Detail & Related papers  (2023-03-13T06:40:19Z)
• Gradient-descent quantum process tomography by learning Kraus operators [63.69764116066747]
  We perform quantum process tomography (QPT) for both discrete- and continuous-variable quantum systems. We use a constrained gradient-descent (GD) approach on the so-called Stiefel manifold during optimization to obtain the Kraus operators. The GD-QPT matches the performance of both compressed-sensing (CS) and projected least-squares (PLS) QPT in benchmarks with two-qubit random processes.
  arXiv  Detail & Related papers  (2022-08-01T12:48:48Z)
• 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)
• Compact quantum kernel-based binary classifier [2.0684234025249717]
  We present the simplest quantum circuit for constructing a kernel-based binary classifier. The number of qubits is reduced by two and the number of steps is reduced linearly. Our design also provides a straightforward way to handle an imbalanced data set.
  arXiv  Detail & Related papers  (2022-02-04T14:30:53Z)
• Quasiprobabilistic state-overlap estimator for NISQ devices [0.39583175274885335]
  A key concept, the state overlap between two quantum states, offers a natural tool to verify and cross-validate quantum simulators and quantum computers. Here, we demonstrate a practical approach for measuring the overlap between quantum states based on a factorable quasiprobabilistic representation of the states.
  arXiv  Detail & Related papers  (2021-12-22T01:51:31Z)
• Programming a quantum computer with quantum instructions [39.994876450026865]
  We use a density matrixiation protocol to execute quantum instructions on quantum data. A fixed sequence of classically-defined gates performs an operation that uniquely depends on an auxiliary quantum instruction state. The utilization of quantum instructions obviates the need for costly tomographic state reconstruction and recompilation.
  arXiv  Detail & Related papers  (2020-01-23T22:43:29Z)

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.