New Trends in Quantum Information

SSRN Electronic Journal, 2021

Speedy developments in Quantum Technologies and Computing with far reaching potential applications in non-traditional fields of finance, bio-medical, biochemistry , etc., make it imperative that fundamentals of Quantum Technologies are well explained and understood. Meanwhile, paradigms of so-called quantum non-locality, wave function (WF) "collapse", "Schrödinger cat" and some other historically popular misconceptions continue to stir controversies, feed mysteries around quantum phenomena and confuse prospective users. In this regard we argue that above misinterpretations stem essentially from classically minded and experimentally unverifiable perceptions, recasting and fitting the Principle of Superposition and key experimental details into classical terms and logic. Further, we revisit key components of general quantum measurement protocols-analyzers and detectors-and explain in this context paradoxes of WF collapse and Schrödinger cat. Then to demystify and clarify the concept of entanglement in multi-component systems (comprised of photons, electrons, atoms and even small macro-objects) and longdistance correlations, we remind that quantum measurements routinely reveal correlations mandated by conservation laws in each individual realization. Remarkably, this "correlation-by-initial conditions" (in addition to traditional "correlation-byinteractions") is by no means an exclusive quantum feature, but also has it analogiesin simplified form though-in Classical Mechanics (CM). However, an appearance and understanding of those correlations in Quantum Mechanics (QM) is governed by the wave-particle duality, forgetting of which leads to endless line of paradoxes. We keep reiterating that QM is not a dynamical theory in the same sense the CM is-it is a statistical theory, as established in 1926 by Born's postulate. That is, while QM enforces conservations laws and ensuing correlations in each individual outcome, it does not indicate how exactly a specific outcome is selected. This selection remains fundamentally random and represents true randomness of QM, the latter being a statistical paradigm with a WF standing for a complex-valued amplitude of a distribution function. We note in conclusion that, although a quantum logic is admittedly a challenge for classical imagination, mechanistically complementing quantum foundations by classically minded expectations trivializes true quantum effects to primitive classical constructions and gives rise to a mysteriously omnipresent non-locality.

2000

The paper is intended to be a survey of all the important aspects and results that have shaped the field of quantum computation and quantum information. The reader is first familiarized with those features and principles of quantum mechanics providing a more efficient and secure information processing. Their applications to the general theory of information, cryptography, algorithms, computational complexity and error-correction are then discussed. Prospects for building a practical quantum computer are also analyzed.

Nature, 2000

This Chapter deals with theoretical developments in the subject of quantum information and quantum computation, and includes an overview of classical information and some relevant quantum mechanics. The discussion covers topics in quantum communication, quantum cryptography, and quantum computation, and concludes by considering whether a perspective in terms of quantum information sheds new light on the conceptual problems of quantum mechanics.

2009

We are witnesses nowadays in physics to an intense effort to built a quantum computer. In this essay, I point out that the failure of this enterprize could be in fact more intellectually exciting than its success. I conjecture that, despite the fact that we do not know any law of nature that would prevent us from building such a machine, it might not be possible, after all, to scale up the few qubits that have been realized so far. If this turns out to be the case, the consequences could be truly amazing: it would mean that quantum mechanics is indeed an incomplete description of reality, as Einstein thought, and it would also imply that certain types of computation and the knowledge derived from it are fundamentally inaccessible.

Quantum Information Processing and Quantum Error Correction, 2012

Nature, 2010

Quantum mechanics-the theory describing the fundamental workings of nature-is famously counterintuitive: it predicts that a particle can be in two places at the same time, and that two remote particles can be inextricably and instantaneously linked. These predictions have been the topic of intense metaphysical debate ever since the theory's inception early last century. However, supreme predictive power combined with direct experimental observation of some of these unusual phenomena leave little doubt as to its fundamental correctness. In fact, without quantum mechanics we could not explain the workings of a laser, nor indeed how a fridge magnet operates. Over the last several decades quantum information science has emerged to seek answers to the question: can we gain some advantage by storing, transmitting and processing information encoded in systems that exhibit these unique quantum properties? Today it is understood that the answer is yes. Many research groups around the world are working towards one of the most ambitious goals humankind has ever embarked upon: a quantum computer that promises to exponentially improve computational power for particular tasks. A number of physical systems, spanning much of modern physics, are being developed for this task-ranging from single particles of light to superconducting circuits-and it is not yet clear which, if any, will ultimately prove successful. Here we describe the latest developments for each of the leading approaches and explain what the major challenges are for the future.

International journal for research in applied science and engineering technology ijraset, 2020

Quantum computing is a locale of figuring focused on making PC development reliant on the norms of quantum speculation, which explains the direct of imperativeness and material on the atomic and subatomic levels. Conventional PCs that we use today can simply encode information in bits that take the estimation of 1 or 0. This confines their ability. Quantum enlisting, on the other hand, uses quantum bits or qubits. It handles the unique limit of subatomic participles that licenses them to exist in more than one state for instance a 1 and a 0 at the same time. Superposition and trap are two features of quantum material science on which these supercomputers are based. This empowers quantum PCs to manage exercises at speeds exponentially higher than common PCs and at significantly lesser imperativeness usage

Reports on Progress in Physics, 1998

The subject of quantum computing brings together ideas from classical information theory, computer science, and quantum physics. This review aims to summarise not just quantum computing, but the whole subject of quantum information theory. Information can be identified as the most general thing which must propagate from a cause to an effect. It therefore has a fundamentally important role in the science of physics. However, the mathematical treatment of information, especially information processing, is quite recent, dating from the mid-twentieth century. This has meant that the full significance of information as a basic concept in physics is only now being discovered. This is especially true in quantum mechanics. The theory of quantum information and computing puts this significance on a firm footing, and has lead to some profound and exciting new insights into the natural world. Among these are the use of quantum states to permit the secure transmission of classical information (quantum cryptography), the use of quantum entanglement to permit reliable transmission of quantum states (teleportation), the possibility of preserving quantum coherence in the presence of irreversible noise processes (quantum error correction), and the use of controlled quantum evolution for efficient computation (quantum computation). The common theme of all these insights is the use of quantum entanglement as a computational resource.

2007

Quantum Computation (QC) is a type of computation where unitary and measurement operations are executed on linear superpositions of basis states. This paper provides a brief introduction to QC. We begin with a discussion of basic models for QC such as quantum TMs, quantum gates and circuits and related complexity results. We then discuss a number of topics in quantum information theory, including bounds for quantum communication and I/O complexity, methods for quantum data compression. and quantum error correction (that is, techniques for decreasing decoherence errors in QC), Furthermore, we enumerate a number of methodologies and technologies for doing QC. Finally, we discuss resource bounds for QC including bonds for processing time, energy and volume, particularly emphasizing challenges in determining volume bounds for observation apperatus. Reversible Computations are computations where each state transformation is a reversible function, so that any computation can be reversed w...