Quantum device

The relationships between thermodynamic entropy and Shannon s information-theoretic entropy and between physics and computation have been explored and hotly debated ever since. It is now well known, for example, that computers can, in principle, provide an arbitrary amount of reliable computation per kT of dissipated energy ([benu73], [fredkin82] see also the discussion in section 6.4). Whether a dissipationless computer can be built in practice, remains an open problem. We must also remember that computers are themselves physical (and therefore, ultimately, quantum) devices, so that any exploration of the limitations of computation will be inextricably linked with the fundamental limitations imposed by the laws of physics. 

Photons in quantum optical cavities also constitute excellent qubit candidates [52]. Resonant coupling of atoms with a single mode of the radiation field was experimentally achieved 25 years ago [53], and eventually the coherent coupling of quantum optical cavities with atoms or (simple) molecules was suggested as a means to achieve stable quantum memories in a hybrid quantum processor [54]. There might be a role to play for molecular spin qubits in this kind of hybrid quantum devices that combine solid-state with flying qubits. 

R.J. Matyi, in Heterostructures and Quantum Devices (VLSI Electronics Microstructure Science), W.R. Frensley, N.G. Einspruch (eds.), Academic Press, San Diego, 1994, Ch. 2. 

Razeghi M (2003) Overview of antimonide based III-V semiconductor epitaxial layers and their applications at the center for quantum devices. European Physical Journal-Applied Physics 23(3), 149-205... 

Until now, the most sensible basic interacting quantum device known to us is the photon. Nevertheless, if the photon possesses an inner structure, as assumed in de Broglie s model, it would imply measurements beyond the photon limit. Since it was assumed that the quantum systems are to be described by local finite wavelets in the derivation of the new uncertainty relations, the measurement space resulting from those general relations must depend on the size of the basic wavelet used. As the width of the analyzing wavelet changes, the measurement scale also changes. This can be seen in the plot in Fig. 20. 

So far, we have tried to form very fine dot arrays on Si substrate for quantum devices and optical and magnetic recording media [3-7] since Hosaka et al. introduced the EB drawing system comprised of a field-emission... 

T. Ravuri, V. A. Mandelshtam, and H. S. Taylor, Calculation of transmission and resonance properties for quantum devices, to be published. 

Zimmerman, J.E., Thiene, R, and Hardings, 1 1970. Design and operation of stable rf biased superconducting point-contact quantum devices. /. Appl. Phys. 41 1572. 

Well, first of all, there are the ingenious experiments designed to show us that quantum effects can, indeed, appear in the macroscopic realm. In the form of SQUID devices, with their superimposed superconducting currents, such macroscopic quantum devices can become practical measuring instruments. And there are such delicate laboratory experiments such as the preparation of macroscopic collections of atoms in a single degenerate Bose-Einstein state. But now the claim might be that such quantum effects, if not limited to the microscopic, are, perhaps, limited to special, technically prepared situations of scientific artifacts. 

As the dimensionality of metals is reduced from the 3-dimensional bulk system to the 1-dimensional wire, the electronic or magnetic properties are changed drastically [26], With the advancement in the experimental techniques to fabricate the metal nanowires, we anticipate the possibilities of incorporating them in futuristic electronic/optoelectronic devices such as quantum devices, magnetic storage, nanoprobes, and spintronics. 

A number of difficulties have to be resolved to create successful devices. These include efficient spin injection into semiconductors and heterostructures, and a search for new spin-polarized materials. Other effects potentially important for spintronic devices include optical and electrical manipulation of ferromagnetism, current-induced switching and precessing of magnetization, and the possibility of a long coherence time for optically excited spins in semiconductors. For a good overview of the issues in spin electronics, including the prospects for spintronic quantum devices, see [3.118]. 

K. Goser, P. Glosekotter, and J. Dienstuhl, Nanoelectronics and Nanosystems From Transistors to Molecular and Quantum Devices, Springer-Verlag, 2004. 

Fu, Y., 8e Willander, M. (1999). Chapter 1 Elemental and compound semiconductors. In Physical model of semiconductor quantum devices (pp. 1-22). Boston Kluwer. 

Individual quantum devices must be precisely engineered. The accuracy threshold for quantum computing suggests that the variability between quantum logical devices must differ by no more than 1 part in 10. ... 

The second reason for the interest in quantum devices is that the energy consumption of a computation can be minimized. This is important since in current computer technology heat production is one of the factors that limit speed and size reduction. 

An ideal quantum device works in a reversible way due to the unitary evolution according to the Schrodinger equation. This does not constitute a problem. It has been shown that the necessary reversibility is not an obstacle to constructing any desired computer in an efficient way Universal computation can be done by reversible gates [13-15]. No essential additional expenditure in space and time is necessary [16-18]. 

EDMR has allowed several different unusual experiments. For example, neutral arsenic dopants interacting with a 2D electron gas have been studied with continuous-wave EDMR at 9.7 GHz and 94 GHz. The Anderson-Mott transition between conduction by sequential tunneling through isolated dopant atoms, and conduction through thermally activated impurity Hubbard bands has been studied in arrays of a few arsenic dopant atoms in a silicon transistor. Single erbium spins with resolved hyperfine structure have been electrically detected after resonant optical excitation. The use of the valley degree of freedom has been eonsidered with dopants in silicon both experimentally and theoretically. The quantum confinement due to silicon nanowires may inerease the temperatures where silicon donor quantum devices ean operate. ... 

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