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The primary consideration in developing new material platforms for quantum applications is to optimize coherence. Despite its importance, decoherence processes remains challenging to experimentally interrogate and quantify. In this…

Quantum Physics · Physics 2025-09-25 Albert Liu , Matthew W. Day , Steven T. Cundiff

We report the experimental demonstration of a one-way quantum protocol reliably operating in the presence of decoherence. Information is protected by designing an appropriate decoherence-free subspace for a cluster state resource. We…

Quantum Physics · Physics 2009-11-13 R. Prevedel , M. S. Tame , A. Stefanov , M. Paternostro , M. S. Kim , A. Zeilinger

We develop a structure theory for decoherence-free subspaces and noiseless subsystems that applies to arbitrary (not necessarily unital) quantum operations. The theory can be alternatively phrased in terms of the superoperator perspective,…

Quantum Physics · Physics 2009-11-11 Man-Duen Choi , David W. Kribs

The temporal evolution of a quantum system can be characterized by quantum process tomography, a complex task that consumes a number of physical resources scaling exponentially with the number of subsystems. An alternative approach to the…

The results of quantum process tomography on a three-qubit nuclear magnetic resonance quantum information processor are presented, and shown to be consistent with a detailed model of the system-plus-apparatus used for the experiments. The…

Dynamical decoupling can enforce a symmetry on the dynamics of an open quantum system. Here we develop an efficient dynamical-decoupling-based strategy to create the decoherence-free subspaces (DFSs) for a set of qubits by optimally…

Quantum Physics · Physics 2019-04-17 Jiang Zhang , Zheng-Yang Zhou , Lian-Ao Wu , J. Q. You

The characterization of quantum dynamics is a fundamental and central task in quantum mechanics. This task is typically addressed by quantum process tomography (QPT). Here we present an alternative "direct characterization of quantum…

Quantum Physics · Physics 2007-05-23 M. Mohseni , D. A. Lidar

A new method of quantum state tomography for quantum information processing is described. The method based on two-dimensional Fourier transform technique involves detection of all the off-diagonal elements of the density matrix in a…

Quantum Physics · Physics 2009-11-07 Ranabir Das , T. S. Mahesh , Anil Kumar

We present a two-step protocol for quantum measurement tomography that is light on classical co-processing cost and still achieves optimal sample complexity in the system dimension. Given measurement data from a known probe state ensemble,…

Quantum Physics · Physics 2025-12-01 Leonardo Zambrano , Sergi Ramos-Calderer , Richard Kueng

The characterization of a quantum device is a crucial step in the development of quantum experiments. This is accomplished via Quantum Process Tomography, which combines the outcomes of different projective measurements to deliver a…

Quantum Physics · Physics 2025-06-26 Francesco Di Colandrea , Nazanin Dehghan , Alessio D'Errico , Ebrahim Karimi

The exchange interaction between identical qubits in a quantum information processor gives rise to unitary two-qubit errors. It is shown here that decoherence free subspaces (DFSs) for collective decoherence undergo Pauli errors under…

Quantum Physics · Physics 2016-09-08 Daniel A. Lidar , David Bacon , Julia Kempe , K. Birgitta Whaley

Quantum computation that combines the coherence stabilization virtues of decoherence-free subspaces and the fault tolerance of geometric holonomic control is of great practical importance. Some schemes of adiabatic holonomic quantum…

Quantum Physics · Physics 2015-06-11 G. F. Xu , J. Zhang , D. M. Tong , Erik Sjoqvist , L. C. Kwek

There has been tremendous progress in the physical realization of quantum computing hardware in recent times, bringing us closer than ever before to realizing the promise of quantum computing. However, noise continues to pose a crucial…

Proposals for scalable quantum computing devices suffer not only from decoherence due to the interaction with their environment, but also from severe engineering constraints. Here we introduce a practical solution to these major concerns,…

Quantum Physics · Physics 2009-11-07 Mark S. Byrd , Daniel A. Lidar

Efficacious quantum information processing relies on extended coherence and precise control. Investigating the limitations surrounding quantum processors is vital for their advancement. In their operation, one challenge is inadvertent wave…

Quantum Physics · Physics 2024-05-14 Alfred Li , Herschel A. Rabitz , Benjamin Lienhard

We study a model of a quantum spin register interacting with an environment of spin particles in quantum-measurement limit. In the limit of collective decoherence we obtain the form of state vectors that constitute high-dimensional…

Quantum Physics · Physics 2014-09-12 Paweł Należyty , Dariusz Chruściński

The reconstruction of density matrices from measurement data (quantum state tomography) is the most comprehensive method for assessing the accuracy and performance of quantum devices. Existing methods to reconstruct two-photon density…

Quantum Physics · Physics 2025-03-12 Salini Rajeev , Mayukh Lahiri

Decoherence-free subspaces (DFS) in systems of dipole-dipole interacting multi-level atoms are investigated theoretically. It is shown that the collective state space of two dipole-dipole interacting four-level atoms contains a…

Quantum Physics · Physics 2009-11-13 M. Kiffner , J. Evers , C. H. Keitel

Decoherence-free subspaces allow for the preparation of coherent and entangled qubits for quantum computing. Decoherence can be dramatically reduced, yet dissipation is an integral part of the scheme in generating stable qubits and…

Quantum Physics · Physics 2009-11-07 Ben Tregenna , Almut Beige , Peter L. Knight

Designing quantum processors is a complex task that demands advanced verification methods to ensure their correct functionality. However, traditional methods of comprehensively verifying quantum devices, such as quantum process tomography,…

Quantum Physics · Physics 2025-08-04 Keren Li , Peng Yan , Hanru Jiang , Nengkun Yu