Magnetic Nanoparticles Arrays for Quantum Calculations

2013 ◽  
Vol 718-720 ◽  
pp. 102-106
Author(s):  
Konstantin Nefedev ◽  
Vitalii Kapitan ◽  
Yuriy Shevchenko
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Quantum Computer ◽  
Magnetic State ◽  
Quantum Superposition ◽  
Magnetostatic Field ◽  
Magnetic Dipoles ◽  
Ordered Array ◽  
Quantum Phenomena ◽  
Magnetic States

In frames of a quantum computer implementation, the ordered array of magnetic dipoles nanoparticles is considered. The phase space calculated for system of dipoles, which interact through long-range magnetostatic field. The behavior of nanoarchitectures in an external magnetic field is studied. The degeneracy of the equilibrium magnetic states depending on the value of an external magnetic field and the spin excess of configurations are determined. The presence of degeneration is a classical analog of quantum superposition, and distribution of probability of magnetic state is a classical representation of such quantum phenomena as entanglement.

scholarly journals MINIMIZATION OF NONRESONANT EFFECTS IN A SCALABLE ISING SPIN QUANTUM COMPUTER

2004 ◽  
Vol 02 (03) ◽  
pp. 379-392 ◽  
Author(s):  
G. P. BERMAN ◽  
D. I. KAMENEV ◽  
V. I. TSIFRINOVICH
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Quantum Computer ◽  
One Dimensional ◽  
Ising Spin ◽  
Spin Quantum ◽  
Computer Based ◽  
Frequency Offsets ◽  
Optimal Values ◽  
Large Frequency

The errors caused by the transitions with large frequency offsets (nonresonant transitions) are calculated analytically for a scalable solid-state quantum computer based on a one-dimensional spin chain with Ising interactions between neighboring spins. Selective excitations of the spins are enabled by a uniform gradient of the external magnetic field. We calculate the probabilities of all unwanted nonresonant transitions associated with the flip of each spin with nonresonant frequency and with flips of two spins: one with resonant and one with nonresonant frequencies. It is shown that these errors oscillate with changing gradient of the external magnetic field. Choosing the optimal values of this gradient allows us to decrease these errors by 50%.

MINIMAL EXECUTION TIME OF SHOR'S ALGORITHM AT LOW TEMPERATURES

2009 ◽  
Vol 07 (01) ◽  
pp. 287-296
Author(s):  
M. A. AVILA
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Execution Time ◽  
Low Temperatures ◽  
Quantum Computer ◽  
Common Belief ◽  
Zero Temperature ◽  
Decoherence Time ◽  
Shor's Algorithm ◽  
The Common

The minimal time, T Shor , in which a one-way quantum computer can execute Shor's algorithm is derived. In the absence of an external magnetic field, this quantity diverges at very small temperatures. This result coincides with that of Anders et al. obtained simultaneously to ours but using thermodynamical arguments. Such divergence contradicts the common belief that it is possible to do quantum computation at low temperatures. It is shown that in the presence of a weak external magnetic field, T Shor becomes a quantized quantity which vanishes at zero temperature. Decoherence is not a problem because T Shor /τ dec < 10-9, where τdec is decoherence time.

scholarly journals Dynamics of charged particles and magnetic dipoles around magnetized quasi-Schwarzschild black holes

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
Bakhtiyor Narzilloev ◽  
Javlon Rayimbaev ◽  
Ahmadjon Abdujabbarov ◽  
Bobomurat Ahmedov ◽  
Cosimo Bambi
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
External Magnetic Field ◽  
Coupling Parameter ◽  
Charged Particles ◽  
Kerr Black Hole ◽  
Rotation Parameter ◽  
Magnetic Dipoles ◽  
Deviation Parameter

AbstractIn the present paper, we have investigated the motion of charged particles together with magnetic dipoles to determine how well the spacetime deviation parameter $$\epsilon $$ ϵ and external uniform magnetic field can mimic the spin of a rotating Kerr black hole. Investigation of charged particle motion has shown that the deviation parameter $$\epsilon $$ ϵ in the absence of an external magnetic fields can mimic the rotation parameter of the Kerr spacetime up to $$a/M \approx 0.5$$ a / M ≈ 0.5 . The combination of an external magnetic field and deviation parameter can do even a better job mimicking the rotation parameter up to $$a/M\simeq 0.93$$ a / M ≃ 0.93 , which corresponds to the rapidly rotating case. Study of the dynamics of the magnetic dipoles around quasi-Schwarzschild black holes in the external magnetic field has shown that there are degeneracy values of the ISCO radius of test particles at $$\epsilon _{cr}>\epsilon \ge 0.35$$ ϵ cr > ϵ ≥ 0.35 which may lead to two different values of the innermost stable circular orbit (ISCO) radius. When the deviation parameter is in the range of $$\epsilon \in (-1,\ 1)$$ ϵ ∈ ( - 1 , 1 ) , it can mimic the spin of a rotating Kerr black hole in the range $$a/M \in (0.0537, \ 0.3952)$$ a / M ∈ ( 0.0537 , 0.3952 ) for magnetic dipoles with values of the magnetic coupling parameter $$\beta \in [-0.25,\ 0.25]$$ β ∈ [ - 0.25 , 0.25 ] in corotating orbits.

Influence of an External Magnetic Field on Injected Charges of a Cr2O3/Fe/CeO2/Si MIS Capacitor

2009 ◽  
Vol 421-422 ◽  
pp. 157-160
Author(s):  
Takeshi Yokota ◽  
Shotaro Murata ◽  
Shinya Kito ◽  
Manabu Gomi
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Electric Field ◽  
Magnetic Materials ◽  
Magnetic State ◽  
Oxygen Deficiency ◽  
Carrier Injection ◽  
Window Width ◽  
Injection Process ◽  
Mis Capacitor

We investigated the influence of an external magnetic field for the carrier injection process of a metal (Au) / insulator (Cr2O3/Fe/CeO2) / semiconductor (Si) (MIS) capacitor, in which the insulator consists of magnetic materials. By applying an electric field, electrons propagating through the CeO2 layer from Si were injected into the Fe or an oxygen deficiency layer formed around the Fe layer. When a magnetic field was applied, the hysteresis window width of this capacitor was reduced. I-V curve analyses under a magnetic field revealed that this reduction was more likely due to the magnetic state of the Fe layer and the interaction between Fe and Cr2O3.

Hydromagnetic radiation from electric and magnetic dipoles in the magnetosphere

1969 ◽  
Vol 47 (16) ◽  
pp. 1643-1656 ◽  
Author(s):  
A. K. Sundaram
Keyword(s):  
Magnetic Field ◽  
Magnetic Dipole ◽  
Electric Dipole ◽  
Static Field ◽  
Radiation Characteristics ◽  
Magnetostatic Field ◽  
Magnetic Dipoles ◽  
The Waves ◽  
Dipole Sources ◽  
The Magnetic Field

This paper deals with the radiation characteristics of elementary electric and magnetic dipoles in a homogeneous, anisotropic, cold plasma of infinite extent with a uniform magnetostatic field. The cases treated include the electromagnetic sources taken parallel and perpendicular to the magnetostatic field. In all cases expressions for the field components are obtained which are valid at frequencies well below the ion cyclotron frequency. It is found that electric and magnetic dipole sources when oriented perpendicular to the magnetic field excite both ordinary and extraordinary modes. For the ordinary mode, the waves are guided in both directions within cones of small apex angle aligned with the static field. When the dipole sources are aligned with the magnetic field, it is found that the electric dipole excites only the ordinary mode leading to guided wave propagation, while the magnetic dipole excites only the extraordinary mode. In all cases the waves propagate at Alfvén speed. The radiation characteristics are isotropic for the extraordinary mode excited by the perpendicular electric dipole and are nearly isotropic for the aligned magnetic dipole. For other cases the radiated power is concentrated in opposite directions along the static field.

Quantum Double Dot as Quantum Computer Unit

2016 ◽  
pp. 3500-3506
Author(s):  
A. M. Khalaf ◽  
Z. Ali ◽  
Sh. Abdelfattah ◽  
A. M. Selim
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
External Magnetic Field ◽  
Quantum Computer ◽  
Double Quantum ◽  
Quantum Double ◽  
Molecular Physics ◽  
Double Quantum Dots ◽  
Magnetization Behavior ◽  
Computer Unit

In this work, we have investigated the exchange interaction of two electrons in double lateral quantum dot (which is the base of quantum gate) under effect of external magnetic field, electric field and inter dot distance between double dots. From similarity between double quantum dots and molecule, we have used molecular physics approaches (Hitler – London and Hund – Mullikan approximation method) to investigate our system. We also show the magnetization behavior as function of magnetic field.

Micromagnetic Simulation of CoFe Magnetic Nanorings: Switching Behavior in External Magnetic Field

2013 ◽  
Vol 710 ◽  
pp. 80-84 ◽  
Author(s):  
Zhen Gang Guo ◽  
Li Qing Pan ◽  
Hong Mei Qiu ◽  
M. Yasir Rafique ◽  
Shuai Zeng
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetization Reversal ◽  
Domain Walls ◽  
Vortex State ◽  
Switching Behavior ◽  
Switching Field ◽  
Reversal Process ◽  
Magnetic States ◽  
Magnetization Processes

The magnetization reversal processes of magnetic nanorings (Co50Fe50) with different geometric shapes are investigated. In addition to the expected onion and vortex magnetization states, other metastable states are observed in the magnetization processes. We anatomize the formation and transition of magnetic states, and the propagation and annihilation of domain walls in the reversal process through the dynamic picture. Phase diagrams for the magnetization switching behavior depending on the geometric parameters are presented. The simulation shows that the vortex state is stabilized in thick and narrow rings. The switching field from vortex to onion states turns out to increase with thickness and decrease with width and diameter.

π Phase Superconductivity and Magnetism in Ferromagnet / Superconductor / Ferromagnet Trilayers

2009 ◽  
Vol 152-153 ◽  
pp. 512-517
Author(s):  
Mansur G. Khusainov ◽  
Yurii N. Proshin
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Boundary Value Problem ◽  
Total Momentum ◽  
Electron Interaction ◽  
Exchange Field ◽  
Two Phase ◽  
High Tc ◽  
Short Period ◽  
Magnetic States

On the base of new boundary-value problem for the Eilenberger function we investigate the superconducting and magnetic states in ferromagnet/superconductor (FM/S) nanostructures, where superconductivity is a superposition of the BCS pairing with zero total momentum in the S layers and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing with nonzero 3D coherent momentum k in the FM layers. We originally study the interplay between the BCS and FFLO states in the pure thin FM/S/FM trilayers and two novel -phase superconducting states with electron-electron repulsion in the FM layers are predicted. The modulated FFLO states are possible in such trilayers only in presence of external magnetic field at suitable parameters of the FM and S layers. In the FM/S superlattices there are also two -phase magnetic states (0 and ) with compensation of the exchange field paramagnetic effect. This fact allows us to explain a surprisingly high Tc ~ 5K in the short period Gd/La superlattice and to predict the sign and value of the electron-electron interaction in the ferromagnetic Gd metal.

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