From quantum information to quantum computer and chaos

2000 ◽  
Author(s):  
Masanori Ohya
Keyword(s):  
Quantum Information ◽  
Quantum Computer

The Dawn of Quantum Information

2020 ◽  
pp. 258-270
Author(s):  
Gershon Kurizki ◽  
Goren Gordon
Keyword(s):  
Quantum Information ◽  
Large Scale ◽  
Quantum Computer ◽  
Quantum Algorithm ◽  
Single Step ◽  
Weather Forecasts ◽  
State Of Mind ◽  
Process Simulations ◽  
Superposition States ◽  
Quantum Revolution

Henry and Eve have finally tested their quantum computer (QC) with resounding success! It may enable much faster and better modelling of complex pharmaceutical designs, long-term weather forecasts or brain process simulations than classical computers. A 1,000-qubit QC can process in a single step 21000 possible superposition states: its speedup is exponential in the number of qubits. Yet this wondrous promise requires overcoming the enormous hurdle of decoherence, which is why progress towards a large-scale QC has been painstakingly slow. To their dismay, their QC is “expropriated for the quantum revolution” in order to share quantum information among all mankind and thus impose a collective entangled state of mind. They set out to foil this totalitarian plan and restore individuality by decohering the quantum information channel. The appendix to this chapter provide a flavor of QC capabilities through a quantum algorithm that can solve problems exponentially faster than classical computers.

scholarly journals APPLICATIONS OF ATOMIC ENSEMBLES IN DISTRIBUTED QUANTUM COMPUTING

2010 ◽  
Vol 08 (01n02) ◽  
pp. 181-218 ◽  
Author(s):  
MARCIN ZWIERZ ◽  
PIETER KOK
Keyword(s):  
Quantum Information ◽  
Quantum Computation ◽  
Quantum Computer ◽  
Success Probability ◽  
Quantum Memory ◽  
Quantum Network ◽  
Atomic Ensembles ◽  
Cluster States ◽  
Ghz States ◽  
Single Qubit

Thesis chapter. The fragility of quantum information is a fundamental constraint faced by anyone trying to build a quantum computer. A truly useful and powerful quantum computer has to be a robust and scalable machine. In the case of many qubits which may interact with the environment and their neighbors, protection against decoherence becomes quite a challenging task. The scalability and decoherence issues are the main difficulties addressed by the distributed model of quantum computation. A distributed quantum computer consists of a large quantum network of distant nodes — stationary qubits which communicate via flying qubits. Quantum information can be transferred, stored, processed and retrieved in decoherence-free fashion by nodes of a quantum network realized by an atomic medium — an atomic quantum memory. Atomic quantum memories have been developed and demonstrated experimentally in recent years. With the help of linear optics and laser pulses, one is able to manipulate quantum information stored inside an atomic quantum memory by means of electromagnetically induced transparency and associated propagation phenomena. Any quantum computation or communication necessarily involves entanglement. Therefore, one must be able to entangle distant nodes of a distributed network. In this article, we focus on the probabilistic entanglement generation procedures such as well-known DLCZ protocol. We also demonstrate theoretically a scheme based on atomic ensembles and the dipole blockade mechanism for generation of inherently distributed quantum states so-called cluster states. In the protocol, atomic ensembles serve as single qubit systems. Hence, we review single-qubit operations on qubit defined as collective states of atomic ensemble. Our entangling protocol requires nearly identical single-photon sources, one ultra-cold ensemble per physical qubit, and regular photodetectors. The general entangling procedure is presented, as well as a procedure that generates in a single stepQ-qubit GHZ states with success probability psuccess ~ ηQ/2, where η is the combined detection and source efficiency. This is significantly more efficient than any known robust probabilistic entangling operation. The GHZ states form the basic building block for universal cluster states, a resource for the one-way quantum computer.

Computational model underlying the one-way quantum computer

2002 ◽  
Vol 2 (6) ◽  
pp. 443-486
Author(s):  
R. Raussendorf ◽  
H. Briegel
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Computational Model ◽  
Quantum Logic ◽  
Quantum Information Processing ◽  
Quantum Computer ◽  
Quantum Circuit ◽  
Single Step ◽  
Clifford Group ◽  
The One

In this paper we present the computational model underlying the one-way quantum computer which we introduced recently [Phys. Rev. Lett. {\bf{86}}, 5188 (2001)]. The one-way quantum computer has the property that any quantum logic network can be simulated on it. Conversely, not all ways of quantum information processing that are possible with the one-way quantum computer can be understood properly in network model terms. We show that the logical depth is, for certain algorithms, lower than has so far been known for networks. For example, every quantum circuit in the Clifford group can be performed on the one-way quantum computer in a single step.

scholarly journals COMPUTER QUANTISTICI: STATUS E PROSPETTIVE

2020 ◽  
Author(s):  
Lorenzo Maccone
Keyword(s):  
Quantum Information ◽  
Quantum Computation ◽  
Quantum Computer

A quantum computer is a system that is able to process quantum information. In this presentation I’ll briefly explain what is it and what are the main results of the current research in the field of quantum computation.

scholarly journals Quantum Mechanics and the Origin of Life

2004 ◽  
Vol 213 ◽  
pp. 237-244
Author(s):  
Paul Davies
Keyword(s):  
Quantum Mechanics ◽  
Information Processing ◽  
Quantum Information ◽  
Quantum Computation ◽  
Origin Of Life ◽  
Quantum Information Processing ◽  
Quantum Computer ◽  
The Origin Of Life ◽  
Concept Of Information

The race to build a quantum computer has led to a radical re-evaluation of the concept of information. In this paper I conjecture that life, defined as an information processing and replicating system, may be exploiting the considerable efficiency advantages offered by quantum computation, and that quantum information processing may dramatically shorten the odds for life originating from a random chemical soup. The plausibility of this conjecture rests, however, on life somehow circumventing the decoherence effects of the environment. I offer some speculations on ways in which this might happen.

scholarly journals QUANTUM COMPUTER: AN APPLIANCE FOR PLAYING MARKET GAMES

2004 ◽  
Vol 02 (04) ◽  
pp. 495-509 ◽  
Author(s):  
EDWARD W. PIOTROWSKI ◽  
JAN SŁADKOWSKI
Keyword(s):  
Game Theory ◽  
Information Theory ◽  
Quantum Information ◽  
Financial Market ◽  
Quantum Computer ◽  
Quantum Information Theory ◽  
Quantum Computers ◽  
Quantum Game ◽  
Recent Developments ◽  
Quantum Strategies

Recent developments in quantum computation and quantum information theory allow one to extend the scope of game theory for the quantum world. The authors have recently proposed a quantum description of financial market in terms of quantum game theory. This paper contains an analysis of such markets that shows that there are advantages to be gained from using quantum computers and quantum strategies.

Quantum information processing

2009 ◽  
Author(s):  
Stephen Barnett
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Unitary Transformation ◽  
Quantum Information Processing ◽  
Quantum Computer ◽  
Quantum Evolution ◽  
Quantum Computers ◽  
Digital Electronics ◽  
Logic Operations ◽  
And Control

We have seen how information can be encoded onto a quantum system by selecting the state in which it is prepared. Retrieving the information is achieved by performing a measurement, and the optimal measurement in any given situation is usually a generalized measurement. In between preparation and measurement, the information resides in the quantum state of the system, which evolves in a manner determined by the Hamiltonian. The associated unitary transformation may usefully be viewed as quantum information processing; if we can engineer an appropriate Hamiltonian then we can use the quantum evolution to assist in performing computational tasks. Our objective in quantum information processing is to implement a desired unitary transformation. Typically this will mean coupling together a number, perhaps a large number, of qubits and thereby generating highly entangled states. It is fortunate, although by no means obvious, that we can realize any desired multiqubit unitary transformation as a product of a small selection of simple transformations and, moreover, that each of these need only act on a single qubit or on a pair of qubits. The situation is reminiscent of digital electronics, in which logic operations are decomposed into actions on a small number of bits. If we can realize and control a very large number of such operations in a single device then we have a computer. Similar control of a large number of qubits will constitute a quantum computer. It is the revolutionary potential of quantum computers, more than any other single factor, that has fuelled the recent explosion of interest in our subject. We shall examine the remarkable properties of quantum computers in the next chapter. In digital electronics, we represent bit values by voltages: the logical value 1 is a high voltage (typically +5 V) and 0 is the ground voltage (0 V). The voltage bits are coupled and manipulated by transistor-based devices, or gates. The simplest gates act on only one bit or combine two bits to generate a single new bit, the value of which is determined by the two input bits. For a single bit, with value 0 or 1, the only possible operations are the identity (which does not require a gate) and the bit flip.

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