Dynamics of quantum coherence and entanglement in an intrinsic noise model of a V-type qutrit system interacting with a coherent field

2020 ◽  
Vol 95 (8) ◽  
pp. 085101
Author(s):  
A-S F Obada ◽  
A-B A Mohamed ◽  
M Hashem ◽  
M M Elkhateeb
Keyword(s):  
Quantum Coherence ◽  
Intrinsic Noise ◽  
Noise Model ◽  
Coherent Field

scholarly journals Nonlinear Dynamics of a Cavity Containing a Two-Mode Coherent Field Interacting with Two-Level Atomic Systems

2020 ◽  
Vol 10 (20) ◽  
pp. 7150
Author(s):  
E. M. Khalil ◽  
Hashim M. Alshehri ◽  
A.-B. A. Mohamed ◽  
S. Abdel-Khalek ◽  
A.-S. F. Obada
Keyword(s):  
Quantum Coherence ◽  
Intrinsic Noise ◽  
Noise Model ◽  
Atomic Systems ◽  
Dipole Coupling ◽  
Two Photon ◽  
Dipole Interactions ◽  
Coherent Field ◽  
Noise Rate ◽  
Sudden Appearance

This study analytically explored two coupled two-level atomic systems (TLAS) as two qubits interacting with two modes of an electromagnetic field (EMF) cavity via two-photon transitions in the presence of dipole–dipole interactions between the atoms and intrinsic damping. Using special unitary su(1,1) Lie algebra, the general solution of an intrinsic noise model is obtained when an EMF is initially in a generalized coherent state. We investigated the population inversion of two TLAS and the generated quantum coherence of some partitions (including the EMF, two TLAS, and TLAS–EMF). It is possible to generate quantum coherence (mixedness and entanglement) from the initial pure state. The robustness of the quantum coherence produced and the sudden appearance and disappearance of coherence depended not only on dipole–dipole coupling but also on the intrinsic noise rate. The growth of mixedness and entanglement may be enhanced by increasing dipole–dipole coupling, leading to more robustness against intrinsic noise.

scholarly journals Circuit Models and Experimental Noise Measurements of Micropipette Amplifiers for Extracellular Neural Recordings from Live Animals

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Chang Hao Chen ◽  
Sio Hang Pun ◽  
Peng Un Mak ◽  
Mang I Vai ◽  
Achim Klug ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Intrinsic Noise ◽  
Model Systems ◽  
Noise Model ◽  
Noise Sources ◽  
Extracellular Recordings ◽  
Neural Recordings ◽  
Noise Measurements ◽  
Glass Micropipette

Glass micropipettes are widely used to record neural activity from single neurons or clusters of neurons extracellularly in live animals. However, to date, there has been no comprehensive study of noise in extracellular recordings with glass micropipettes. The purpose of this work was to assess various noise sources that affect extracellular recordings and to create model systems in which novel micropipette neural amplifier designs can be tested. An equivalent circuit of the glass micropipette and the noise model of this circuit, which accurately describe the various noise sources involved in extracellular recordings, have been developed. Measurement schemes using dead brain tissue as well as extracellular recordings from neurons in the inferior colliculus, an auditory brain nucleus of an anesthetized gerbil, were used to characterize noise performance and amplification efficacy of the proposed micropipette neural amplifier. According to our model, the major noise sources which influence the signal to noise ratio are the intrinsic noise of the neural amplifier and the thermal noise from distributed pipette resistance. These two types of noise were calculated and measured and were shown to be the dominating sources of background noise forin vivoexperiments.

scholarly journals Modeling and Parallel Operation of Exchange-Biased Delta-E Effect Magnetometers for Sensor Arrays

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7594
Author(s):  
Benjamin Spetzler ◽  
Patrick Wiegand ◽  
Phillip Durdaut ◽  
Michael Höft ◽  
Andreas Bahr ◽  
...  
Keyword(s):  
Detection Limit ◽  
Limit Of Detection ◽  
Sensor Arrays ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Intrinsic Noise ◽  
Magnetic Multilayers ◽  
Noise Model ◽  
Parallel Operation ◽  
Resonance Frequencies

Recently, Delta-E effect magnetic field sensors based on exchange-biased magnetic multilayers have shown the potential of detecting low-frequency and small-amplitude magnetic fields. Their design is compatible with microelectromechanical system technology, potentially small, and therefore, suitable for arrays with a large number N of sensor elements. In this study, we explore the prospects and limitations for improving the detection limit by averaging the output of N sensor elements operated in parallel with a single oscillator and a single amplifier to avoid additional electronics and keep the setup compact. Measurements are performed on a two-element array of exchange-biased sensor elements to validate a signal and noise model. With the model, we estimate requirements and tolerances for sensor elements using larger N. It is found that the intrinsic noise of the sensor elements can be considered uncorrelated, and the signal amplitude is improved if the resonance frequencies differ by less than approximately half the bandwidth of the resonators. Under these conditions, the averaging results in a maximum improvement in the detection limit by a factor of N. A maximum N≈200 exists, which depends on the read-out electronics and the sensor intrinsic noise. Overall, the results indicate that significant improvement in the limit of detection is possible, and a model is presented for optimizing the design of delta-E effect sensor arrays in the future.

Quantum coherence induced by a flux qubit coupled by a resonator coherent field through a two-photon interaction

2021 ◽  
Author(s):  
Abdel-Baset Mohamed ◽  
Hosny A Hessian ◽  
F. S. Al-Duais ◽  
H Eleuch
Keyword(s):  
Sudden Death ◽  
Coherent States ◽  
Quantum Coherence ◽  
Intrinsic Decoherence ◽  
Photon Interaction ◽  
Two Photon ◽  
Coherent Field ◽  
Flux Qubit

Abstract The intrinsic decoherence effects on a flux qubit coupled to a resonator through a two-photon interaction where the resonator field is initially in coherent and even coherent states are investigated. The qubit-resonator entanglement and coherence loss (mixedness) of the system and its subsystems are examined using entropy and negativity. The ability of the qubit-resonator interaction to generate quantum coherence (qubit-resonator entanglement and the mixedness) is shown to be dependent on the initial cavity non-classicality, detuning, and decoherence. For larger values of the qubit-resonator detuning, the initial resonator non-classicality can enhance the generation and stability of quantum coherence. The decoherence degrades the qubit-resonator entanglement and destroys the sudden death-birth entanglement.

Quantitative analysis by reconstruction of HREM focal series

1994 ◽  
Vol 52 ◽  
pp. 740-741
Author(s):  
W. Coene ◽  
A. Thust ◽  
M. Op de Beeck ◽  
D. Van Dyck
Keyword(s):  
Phase Retrieval ◽  
Image Plane ◽  
Initial Guess ◽  
Recursive Least Squares ◽  
Objective Lens ◽  
Electron Wave ◽  
Electron Sources ◽  
Original Algorithm ◽  
Coherent Field ◽  
Direct Interpretation

Compared to conventional electron sources, the use of a highly coherent field-emission gun (FEG) in TEM improves the information resolution considerably. A direct interpretation of this extra information, however, is hampered since amplitude and phase of the electron wave are scrambled in a complicated way upon transfer from the specimen exit plane through the objective lens towards the image plane. In order to make the additional high-resolution information interpretable, a phase retrieval procedure is applied, which yields the aberration-corrected electron wave from a focal series of HRTEM images (Coene et al, 1992).Kirkland (1984) tackled non-linear image reconstruction using a recursive least-squares formalism in which the electron wave is modified stepwise towards the solution which optimally matches the contrast features in the experimental through-focus series. The original algorithm suffers from two major drawbacks : first, the result depends strongly on the quality of the initial guess of the first step, second, the processing time is impractically high.

Unified small-signal-noise model for active microwave devices

1993 ◽  
Vol 140 (1) ◽  
pp. 55 ◽  
Author(s):  
Z.R. Hu ◽  
Z.M. Yang ◽  
V.F. Fusco ◽  
J.A.C. Stewart
Keyword(s):  
Noise Model ◽  
Microwave Devices ◽  
Small Signal ◽  
Signal Noise

Extension of the LTV Phase Noise Model of Electrical Oscillators for the Output Harmonics

2012 ◽  
Vol E95.C (12) ◽  
pp. 1846-1856 ◽  
Author(s):  
Seyed Amir HASHEMI ◽  
Hassan GHAFOORIFARD ◽  
Abdolali ABDIPOUR
Keyword(s):  
Phase Noise ◽  
Noise Model ◽  
Electrical Oscillators

Engineering Electronic Structure to Protect Phase Memory in Molecular Qubits by Minimising Orbital Angular Momentum

2018 ◽  
Author(s):  
Ana Maria Ariciu ◽  
David H. Woen ◽  
Daniel N. Huh ◽  
Lydia Nodaraki ◽  
Andreas Kostopoulos ◽  
...  
Keyword(s):  
Electron Spin ◽  
Quantum Coherence ◽  
Quantum Information Processing ◽  
Pulse Sequences ◽  
Grover Algorithm ◽  
Ligand Shell ◽  
Information Strategies ◽  
Spin Qubit ◽  
Molecular Spin ◽  
The Impact

Using electron spins within molecules for quantum information processing (QIP) was first proposed by Leuenberger and Loss (1), who showed how the Grover algorithm could be mapped onto a Mn12 cage (2). Since then several groups have examined two-level (S = ½) molecular spin systems as possible qubits (3-12). There has also been a report of the implementation of the Grover algorithm in a four-level molecular qudit (13). A major challenge is to protect the spin qubit from noise that causes loss of phase information; strategies to minimize the impact of noise on qubits can be categorized as corrective, reductive, or protective. Corrective approaches allow noise and correct for its impact on the qubit using advanced microwave pulse sequences (3). Reductive approaches reduce the noise by minimising the number of nearby nuclear spins (7-11), and increasing the rigidity of molecules to minimise the effect of vibrations (which can cause a fluctuating magnetic field via spin-orbit coupling) (9,11); this is essentially engineering the ligand shell surrounding the electron spin. A protective approach would seek to make the qubit less sensitive to noise: an example of the protective approach is the use of clock transitions to render spin states immune to magnetic fields at first order (12). Here we present a further protective method that would complement reductive and corrective approaches to enhancing quantum coherence in molecular qubits. The target is a molecular spin qubit with an effective 2S ground state: we achieve this with a family of divalent rare-earth molecules that have negligible magnetic anisotropy such that the isotropic nature of the electron spin renders the qubit markedly less sensitive to magnetic noise, allowing coherent spin manipulations even at room temperature. If combined with the other strategies, we believe this could lead to molecular qubits with substantial advantages over competing qubit proposals.<br>

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