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We extend the argument that spacetimes generated by two timelike particles in D=3 gravity (or equivalently by parallel-moving cosmic strings in D=4) permit closed timelike curves (CTC) only at the price of Misner identifications that…

General Relativity and Quantum Cosmology · Physics 2009-11-19 S. Deser , Alan R. Steif

Recently Burrage, de Rham, Heisenberg and Tolley have constructed eternal, classical solutions with closed timelike curves (CTCs) in a Galileon model coupled to an auxiliary scalar field. These theories contain at least two distinct metrics…

High Energy Physics - Theory · Physics 2012-11-20 Jarah Evslin

Quantum computers and quantum algorithms have made great strides in the last few years and promise improvements over classical computing for specific tasks. Although the current hardware is not yet ready to make real impacts at the time of…

Quantum Physics · Physics 2024-08-28 Nils Quetschlich , Tobias Forster , Adrian Osterwind , Domenik Helms , Robert Wille

A recent paper from Brun et al. has argued that access to a closed timelike curve (CTC) would allow for the possibility of perfectly distinguishing nonorthogonal quantum states. This result can be used to develop a protocol for…

Quantum Physics · Physics 2016-01-19 Lucas Dunlap

The computing ecosystem has always had deep impacts on society and technology and profoundly changed our lives in myriads of ways. Despite decades of impressive Moore's Law performance scaling and other growth in the computing ecosystem…

Emerging Technologies · Computer Science 2019-03-27 Margaret Martonosi , Martin Roetteler

Bennett and Schumacher's postselected quantum teleportation is a model of closed timelike curves (CTCs) that leads to results physically different from Deutsch's model. We show that even a single qubit passing through a postselected CTC…

Quantum Physics · Physics 2012-02-07 Todd A. Brun , Mark M. Wilde

We consider Deutsch's computational model of a quantum system evolving in a spacetime containing closed timelike curves. Although it is known that this model predicts non-linear and non-unitary evolutions of the system, we demonstrate that…

Quantum Physics · Physics 2010-05-12 Richard DeJonghe , Kimberly Frey , Tom Imbo

The quest for quantum computers is motivated by their potential for solving problems that defy existing, classical, computers. The theory of computational complexity, one of the crown jewels of computer science, provides a rigorous…

Statistical Mechanics · Physics 2010-09-10 C. R. Laumann , R. Moessner , A. Scardicchio , S. L. Sondhi

The D-CTC condition, introduced by David Deutsch as a condition to be fulfilled by analogues for processes of quantum systems in the presence of closed timelike curves, is investigated for classical statistical (non-quantum) bi-partite…

Quantum Physics · Physics 2021-10-05 Jürgen Tolksdorf , Rainer Verch

Understanding the relationship between the time-symmetric nature of physical laws and the apparent directionality of causality is a central question in quantum foundations. The standard operational formulation, widely used in quantum…

Quantum Physics · Physics 2025-08-05 Eliot Jean , Ralph Silva , V. Vilasini

Scientists have demonstrated that quantum computing has presented novel approaches to address computational challenges, each varying in complexity. Adapting problem-solving strategies is crucial to harness the full potential of quantum…

Computational Complexity · Computer Science 2024-09-13 Arash Vaezi , Ali Movaghar , Mohammad Ghodsi , Seyed Mohammad Hussein Kazemi , Negin Bagheri Noghrehy , Seyed Mohsen Kazemi

In general relativity, closed timelike curves can break causality with remarkable and unsettling consequences. At the classical level, they induce causal paradoxes disturbing enough to motivate conjectures that explicitly prevent their…

In this comment on S.Lloyd, et al, Phys.Rev.Lett. 106, 040403 (2011), we show that modelling closed timelike curves (CTCs) as post-selected teleportation allows signalling to past times before the creation of the CTC and allows information…

Quantum Physics · Physics 2011-07-26 T. C. Ralph

General relativity allows solutions exhibiting closed timelike curves. Time travel generates paradoxes and quantum mechanics generalizations were proposed to solve those paradoxes. The implications of self-consistent interactions on acausal…

General Physics · Physics 2009-01-05 Florin Moldoveanu

The Quantum Computer Condition (QCC) provides a rigorous and completely general framework for carrying out analyses of questions pertaining to fault-tolerance in quantum computers. In this paper we apply the QCC to the problem of…

Quantum Physics · Physics 2007-05-23 Gerald Gilbert , Michael Hamrick , F. Javier Thayer , Yaakov S. Weinstein

It is not known what the limitations are on using quantum computation to speed up classical computation. An example would be the power to speed up PSPACE-complete computations. It is also not known what the limitations are on the duration…

High Energy Physics - Theory · Physics 2018-02-08 Leonard Susskind

Quantum computers are widely believed have an advantage over classical computers, and some have even published some empirical evidence that this is the case. However, these publications do not include a rigorous proof of this advantage,…

Computational Complexity · Computer Science 2022-09-22 Jonah Librande

A generalization of the action principle of classical mechanics, motivated by the Closed Time Path (CTP) scheme of quantum field theory, is presented to deal with initial condition problems and dissipative forces. The similarities of the…

High Energy Physics - Theory · Physics 2015-06-22 Janos Polonyi

Quantum computers are reaching a level where interactions between classical and quantum computations can happen in real-time. This marks the advent of a new, broader class of quantum circuits: dynamic quantum circuits. They offer a broader…

Quantum Physics · Physics 2023-01-11 Lukas Burgholzer , Robert Wille

Quantum theory (QT) has been confirmed by numerous experiments, yet we still cannot fully grasp the meaning of the theory. As a consequence, the quantum world appears to us paradoxical. Here we shed new light on QT by having it follow from…

Quantum Physics · Physics 2019-02-12 Alessio Benavoli , Alessandro Facchini , Marco Zaffalon