Results 1 
7 of
7
Computation and Hypercomputation
 MINDS AND MACHINES
, 2003
"... Does Nature permit the implementation of behaviours that cannot be simulated computationally? We consider the meaning of physical computationality in some detail, and present arguments in favour of physical hypercomputation: for example, modern scientific method does not allow the specification o ..."
Abstract

Cited by 15 (4 self)
 Add to MetaCart
Does Nature permit the implementation of behaviours that cannot be simulated computationally? We consider the meaning of physical computationality in some detail, and present arguments in favour of physical hypercomputation: for example, modern scientific method does not allow the specification of any experiment capable of refuting hypercomputation. We consider the implications of relativistic algorithms capable of solving the (Turing) Halting Problem. We also reject as a fallacy the argument that hypercomputation has no relevance because noncomputable values are indistinguishable from sufficiently close computable approximations. In addition to
Reversible Arithmetic Coding for Quantum Data Compression
 IEEE Transactions on Information Theory
"... We study the problem of compressing a block of symbols (a block quantum state) emitted by a memoryless quantum Bernoulli source. We present a simpletoimplement quantum algorithm for projecting, with high probability, the block quantum state onto the typical subspace spanned by the leading eigensta ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
We study the problem of compressing a block of symbols (a block quantum state) emitted by a memoryless quantum Bernoulli source. We present a simpletoimplement quantum algorithm for projecting, with high probability, the block quantum state onto the typical subspace spanned by the leading eigenstates of its density matrix. We propose a fixedrate quantum ShannonFano code to compress the projected block quantum state using a per symbol code rate that is slightly higher than the von Neumann entropy limit. Finally, we propose quantum arithmetic codes to efficiently implement quantum ShannonFano codes. Our arithmetic encoder/decoder have a cubic circuit and a cubic computational complexity in the block size. The encoder and decoder are quantummechanical inverses of each other, and constitute an elegant example of reversible quantum computation. Keywords: quantum computation, quantum information theory, quantum measurement, noiseless coding, reversible computation, Schumacher coding, a...
Nondigital Implementation of the Arithmetic of Real Numbers by Means of Quantum Computer Media
, 2002
"... In the framework of a model for quantum computer media, a nondigital implementation of the arithmetic of the real numbers is described. For this model, an elementary storage “cell” is an ensemble of qubits (quantum bits). It is found that to store an arbitrary real number it is sufficient to use fo ..."
Abstract
 Add to MetaCart
In the framework of a model for quantum computer media, a nondigital implementation of the arithmetic of the real numbers is described. For this model, an elementary storage “cell” is an ensemble of qubits (quantum bits). It is found that to store an arbitrary real number it is sufficient to use four of these ensembles and the arithmetical operations can be implemented by fixed quantum circuits.
Quantum Dots: Coulomb Blockade,
"... The continuous minituarization of integrated circuits is going to affect the underlying physics of the future computers. This new physics first came into play as the effect of Coulomb blockade in electron transport through small conducting islands. Then, as the size of the island L continued to shri ..."
Abstract
 Add to MetaCart
The continuous minituarization of integrated circuits is going to affect the underlying physics of the future computers. This new physics first came into play as the effect of Coulomb blockade in electron transport through small conducting islands. Then, as the size of the island L continued to shrink further, the quantum phase coherence length became larger than L leading to mesoscopic fluctuations – fluctuations of the island’s quantum mechanical properties upon small external perturbations. Quantum coherence of the mesoscopic systems is essential for building reliable quantum computer. Unfortunately, one can not completely isolate the system from the environment and its coupling to the environment inevitably leads to the loss of coherence or decoherence. All these effects are to be thoroughly investigated as the potential of the future applications is enormous. In this thesis I find an analytic expression for the conductance of a single electron transistor in the regime when temperature, level spacing, and charging energy of an island are all of the same order. I also study the correction to the spacing between Coulomb blockade peaks due to finite dotlead tunnel couplings. I find analytic
QUANTUM COMPUTER MEDIA 1 Nondigital Implementation of the Arithmetic of Real Numbers by Means of Quantum Computer Media
, 2002
"... Abstract—In the framework of a model for quantum computer media, a nondigital implementation of the arithmetic of the real numbers is described. For this model, an elementary storage “cell ” is an ensemble of qubits (quantum bits). It is found that to store an arbitrary real number it is sufficient ..."
Abstract
 Add to MetaCart
Abstract—In the framework of a model for quantum computer media, a nondigital implementation of the arithmetic of the real numbers is described. For this model, an elementary storage “cell ” is an ensemble of qubits (quantum bits). It is found that to store an arbitrary real number it is sufficient to use four of these ensembles and the arithmetical operations can be implemented by fixed quantum circuits. Key words: quantum media, quantum computer, arithmetic, qubit, qensemble.
NonExponential Electron Spin Decay in Indium Arsenide Quantum Dots
, 2013
"... Electron spins in InAs quantum dots have been studied using a pumpprobe technique that normally yields the T1 spin lifetime, the time required for initially polarized electrons to relax and randomize. Using a circularly polarized laser tuned to the wavelength response of the quantum dots, the spins ..."
Abstract
 Add to MetaCart
Electron spins in InAs quantum dots have been studied using a pumpprobe technique that normally yields the T1 spin lifetime, the time required for initially polarized electrons to relax and randomize. Using a circularly polarized laser tuned to the wavelength response of the quantum dots, the spins are "pumped " into alignment. After alignment, the spins are detected using a second, linearly polarized "probe " laser. The spin response over time is traced out by changing the delay between the two lasers. In contrast with other samples (bulk GaAs and a GaAs quantum well), where the spin response decays exponentially with time, initial data on the quantum dots has shown an unexpected, exponentially decaying sinusoid. This exponentially decaying sinusoid has a decay constant of 190 ns and oscillation frequency of 4.17 MHz, independent of both temperature and magnetic field.
Quantum Information Theory and . . . Quantum Mechanics
, 2004
"... This thesis is a contribution to the debate on the implications of quantum information theory for the foundational problems of quantum mechanics. In Part I an attempt is made to shed some light on the nature of information and quantum information theory. It is emphasized that the everyday notion of ..."
Abstract
 Add to MetaCart
This thesis is a contribution to the debate on the implications of quantum information theory for the foundational problems of quantum mechanics. In Part I an attempt is made to shed some light on the nature of information and quantum information theory. It is emphasized that the everyday notion of information is to be firmly distinguished from the technical notions arising in information theory; noun, hence does not refer to a particular or substance. The popular claim ‘Information is Physical ’ is assessed and it is argued that this proposition faces a destructive dilemma. Accordingly, the slogan may not be understood as an ontological claim, but at best, as a methodological one. A novel argument is provided against Dretske’s (1981) attempt to base a semantic notion of information on ideas from information theory. The function of various measures of information content for quantum systems is explored and the applicability of the Shannon information in the quantum context maintained against the challenge of Brukner and Zeilinger (2001). The phenomenon of quantum teleportation is then explored as a case study serving to emphasize the value of