scholarly journals Fidelity of noisy multiple-control reversible gates

2020 ◽  
Vol 23 (04) ◽  
pp. 385-392
Author(s):  
V.G. Deibuk ◽  
◽  
I.M. Yuriychuk ◽  
I. Lemberski ◽  
◽  
...  
Keyword(s):  
Frequency Control ◽  
Larmor Frequency ◽  
Interaction Constant ◽  
Frequency Noise ◽  
Nuclear Spins ◽  
Multiple Control ◽  
Correct Operation ◽  
Operation Algorithm ◽  
Semiconductor Matrix ◽  
A Chain

The effect of frequency noise on correct operation of the multiple-control Toffoli, Fredkin, and Peres gates has been discussed. In the framework of the Ising model, the energy spectrum of a chain of atoms with nuclear spins one-half in a spinless semiconductor matrix has been obtained, and allowed transitions corresponding to the operation algorithm of these gates have been determined. The fidelities of the obtained transitions were studied depending on the number of control qubits and parameters of the radio-frequency control pulses. It has been shown that correct operation of the Toffoli and Fredkin gates does not depend on the number of control qubits, while the Peres gate fidelity decreases significantly with the increasing number of control signals. The calculated ratios of the Larmor frequency to the exchange interaction constant correspond with the results of other studies.

scholarly journals Ultra-deep optical cooling of coupled nuclear spin-spin and quadrupole reservoirs in a GaAs/(Al,Ga)As quantum well

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mladen Kotur ◽  
Daniel O. Tolmachev ◽  
Valentina M. Litvyak ◽  
Kirill V. Kavokin ◽  
Dieter Suter ◽  
...  
Keyword(s):  
Quantum Well ◽  
Nuclear Spin ◽  
Optical Pumping ◽  
Larmor Frequency ◽  
Spin Splitting ◽  
Magnetic Field Direction ◽  
Nuclear Spins ◽  
Spin Temperature ◽  
Adiabatic Demagnetization ◽  
Selective Cooling

AbstractThe physics of interacting nuclear spins in solids is well interpreted within the nuclear spin temperature concept. A common approach to cooling the nuclear spin system is adiabatic demagnetization of the initial, optically created, nuclear spin polarization. Here, the selective cooling of 75As spins by optical pumping followed by adiabatic demagnetization in the rotating frame is realized in a nominally undoped GaAs/(Al,Ga)As quantum well. The lowest nuclear spin temperature achieved is 0.54 μK. The rotation of 6 kG strong Overhauser field at the 75As Larmor frequency of 5.5 MHz is evidenced by the dynamic Hanle effect. Despite the presence of the quadrupole induced nuclear spin splitting, it is shown that the rotating 75As magnetization is uniquely determined by the spin temperature of coupled spin-spin and quadrupole reservoirs. The dependence of heat capacity of these reservoirs on the external magnetic field direction with respect to crystal and structure axes is investigated.

scholarly journals A Peer Survey on Load Frequency Contol in Isolated Power System with Novel Topologies

2021 ◽  
Vol 11 (1) ◽  
pp. 82-88
Author(s):  
Namburi Nireekshana ◽  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Frequency Control ◽  
Electrical Power ◽  
Load Frequency Control ◽  
Human Beings ◽  
Multiple Control ◽  
Control Techniques ◽  
Load Frequency ◽  
Soft Computing Techniques

Electrical Power systems are paramount intricate system which built by human beings, therefore this type of systems should maintain stable and to get upgrading for upcoming days need multiple control techniques. In these convoluted power systems voltage frequency plays a major role .Hence frequency has to control proper. To control frequency of voltage has three control techniques are primary, secondary and also tertiary frequency control techniques .Thereby second technique also known as Load Frequency Control[1], It is to maintain the desirable frequency even after occurrence of disturbance. Several techniques have been used (like classical, adaptive) to mitigate the power flow disturbances, but drawbacks (parameters tuning, cyber-attacks) are having in these methods. This paper proposes soft computing techniques to build up the operation, control and then stability of the electrical power system.

scholarly journals Broadband 75–85 MHz radiofrequency fields disrupt magnetic compass orientation in night-migratory songbirds consistent with a flavin-based radical pair magnetoreceptor

2022 ◽  
Author(s):  
Bo Leberecht ◽  
Dmitry Kobylkov ◽  
Thiemo Karwinkel ◽  
Sara Döge ◽  
Lars Burnus ◽  
...  
Keyword(s):  
Radical Pair ◽  
Hyperfine Interactions ◽  
Magnetic Compass ◽  
Nuclear Spins ◽  
Compass Orientation ◽  
Migratory Songbirds ◽  
Migratory Songbird ◽  
Behavioural Experiments ◽  
A Chain

AbstractThe light-dependent magnetic compass sense of night-migratory songbirds can be disrupted by weak radiofrequency fields. This finding supports a quantum mechanical, radical-pair-based mechanism of magnetoreception as observed for isolated cryptochrome 4, a protein found in birds’ retinas. The exact identity of the magnetically sensitive radicals in cryptochrome is uncertain in vivo, but their formation seems to require a bound flavin adenine dinucleotide chromophore and a chain of four tryptophan residues within the protein. Resulting from the hyperfine interactions of nuclear spins with the unpaired electrons, the sensitivity of the radicals to radiofrequency magnetic fields depends strongly on the number of magnetic nuclei (hydrogen and nitrogen atoms) they contain. Quantum-chemical calculations suggested that electromagnetic noise in the frequency range 75–85 MHz could give information about the identity of the radicals involved. Here, we show that broadband 75–85 MHz radiofrequency fields prevent a night-migratory songbird from using its magnetic compass in behavioural experiments. These results indicate that at least one of the components of the radical pair involved in the sensory process of avian magnetoreception must contain a substantial number of strong hyperfine interactions as would be the case if a flavin–tryptophan radical pair were the magnetic sensor.

Observation of Atom Rows in Thorium Pyromellitate Using a Field Emission STEM

1977 ◽  
Vol 35 ◽  
pp. 80-81
Author(s):  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Field Emission ◽  
Amorphous Carbon ◽  
Carbon Film ◽  
Dark Field Image ◽  
Dark Field ◽  
Amorphous Carbon Film ◽  
Atomic Size ◽  
Wide Range ◽  
A Chain

It is interesting to observe polymers at atomic size resolution. Some works have been reported for thorium pyromellitate by using a STEM (1), or a CTEM (2,3). The results showed that this polymer forms a chain in which thorium atoms are arranged. However, the distance between adjacent thorium atoms varies over a wide range (0.4-1.3nm) according to the different authors.The present authors have also observed thorium pyromellitate specimens by means of a field emission STEM, described in reference 4. The specimen was prepared by placing a drop of thorium pyromellitate in 10-3 CH3OH solution onto an amorphous carbon film about 2nm thick. The dark field image is shown in Fig. 1A. Thorium atoms are clearly observed as regular atom rows having a spacing of 0.85nm. This lattice gradually deteriorated by successive observations. The image changed to granular structures, as shown in Fig. 1B, which was taken after four scanning frames.

Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 502-503
Author(s):  
Eva-Maria Mandelkow ◽  
Ron Milligan
Keyword(s):  
Electron Microscopy ◽  
Dynamic Instability ◽  
Entire Solution ◽  
Reaction Scheme ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
A Chain ◽  
Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

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