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We consider the task of deciding whether an unknown qubit state falls in a prescribed neighborhood of a reference state. We assume that several copies of the unknown state are given and apply a unitary operation pairwise on them combined…

Quantum Physics · Physics 2018-08-27 Orsolya Kálmán , Tamás Kiss

Quantum experiments usually assume the existence of perfect, classical, reference frames, which allow for the specification of measurement settings (e.g. orientation of the Stern Gerlach magnet in spin measurements) with arbitrary…

Quantum Physics · Physics 2009-12-14 Fabio Costa , Nicholas Harrigan , Terry Rudolph , Caslav Brukner

We consider the class of reference frame independent protocols in d dimensions for quantum key distribution, in which Alice and Bob have one natural basis that is aligned and the rest of their frames are unaligned. We relate existing…

Quantum Physics · Physics 2015-03-19 Le Phuc Thinh , Lana Sheridan , Valerio Scarani

Known quantum error correction schemes are typically able to take advantage of only a limited class of classical error-correcting codes. Entanglement-assisted quantum error correction is a partial solution which made it possible to exploit…

Quantum Physics · Physics 2013-04-24 Yuichiro Fujiwara

Near-term quantum computations are limited by high error rates, the scarcity of qubits and low qubit connectivity. Increasing support for mid-circuit measurements and qubit reset in near-term quantum computers enables qubit reuse that may…

Quantum Physics · Physics 2023-08-02 Sebastian Brandhofer , Ilia Polian , Kevin Krsulich

We analyze the problem of sending, in a single transmission, the information required to specify an orthogonal trihedron or reference frame through a quantum channel made out of N elementary spins. We analytically obtain the optimal…

Quantum Physics · Physics 2009-11-07 E. Bagan , M. Baig , R. Munoz-Tapia

An examination of the concept of using classical degrees of freedom to drive the evolution of quantum computers is given. Specifically, when externally generated, coherent states of the electromagnetic field are used to drive transitions…

Quantum Physics · Physics 2009-10-31 Jeff P. Barnes , Warren S. Warren

The perspective-neutral formulation of quantum reference frames (QRFs) treats observers as quantum systems and describes physics relationally from within the composite system. While frame-change maps and frame-invariant resource sums are…

Quantum Physics · Physics 2025-12-16 Salman Sajad Wani , Saif Al-Kuwari

We derive a bound on the precision of state estimation for finite dimensional quantum systems and prove its attainability in the generic case where the spectrum is non-degenerate. Our results hold under an assumption called local asymptotic…

Quantum Physics · Physics 2019-05-09 Yuxiang Yang , Giulio Chiribella , Masahito Hayashi

Readout errors are a significant source of noise for near term intermediate scale quantum computers. Mismeasuring a qubit as a 1 when it should be 0 occurs much less often than mismeasuring a qubit as a 0 when it should have been 1. We make…

Quantum Physics · Physics 2021-02-10 Rebecca Hicks , Christian W. Bauer , Benjamin Nachman

The fact that quantum mechanics predicts stronger correlations than classical physics is an essential cornerstone of quantum information processing. Indeed, these quantum correlations are a valuable resource for various tasks, such as…

Quantum computers with tens to hundreds of noisy qubits are being developed today. To be useful for real-world applications, we believe that these near-term systems cannot simply be scaled-down non-error-corrected versions of future…

Quantum simulation uses a well-known quantum system to predict the behavior of another quantum system. Certain limitations in this technique arise, however, when applied to specific problems, as we demonstrate with a theoretical and…

Quantum Physics · Physics 2009-11-13 Kenneth R. Brown , Robert J. Clark , Isaac L. Chuang

Quantum computing promises to provide exponential speed-ups to certain classes of problems. In many such algorithms, a classical vector $\mathbf{b}$ is encoded in the amplitudes of a quantum state $\left |b \right >$. However, efficiently…

Quantum Physics · Physics 2022-08-10 Prithvi Gundlapalli , Junyi Lee

We identify optimal quantum error correction codes for situations that do not admit perfect correction. We provide analytic n-qubit results for standard cases with correlated errors on multiple qubits and demonstrate significant…

Quantum Physics · Physics 2015-06-15 Sol H. Jacobsen , Florian Mintert

A common requirement of quantum simulations and algorithms is the preparation of complex states through sequences of 2-qubit gates. For a generic quantum state, the number of gates grows exponentially with the number of qubits, becoming…

Quantum Physics · Physics 2024-07-08 Matan Ben Dov , David Shnaiderov , Adi Makmal , Emanuele G. Dalla Torre

The precise and automated calibration of quantum gates is a key requirement for building a reliable quantum computer. Unlike errors from decoherence, systematic errors can in principle be completely removed by tuning experimental…

Quantum Physics · Physics 2021-01-25 Pascal Cerfontaine , René Otten , Hendrik Bluhm

This thesis is a compilation of research in relativistic quantum information theory, and research in quantum reference frames. The research in the former category provides a fundamental construction of quantum information theory of…

Quantum Physics · Physics 2013-12-18 Matthew C Palmer

We consider quantum communication in the case that the communicating parties not only do not share a reference frame but use imperfect quantum communication channels, in that each channel applies some fixed but unknown unitary rotation to…

Quantum Physics · Physics 2009-11-13 S. J. van Enk

We propose quantum cryptographic protocols to secretly communicate a reference frame- unspeakable information in the sense it cannot be encoded into a string of bits. Two distant parties can secretly align their Cartesian axes by exchanging…

Quantum Physics · Physics 2008-10-22 Giulio Chiribella , Lorenzo Maccone , Paolo Perinotti