Search results for "Computer Science::Emerging Technologies"
showing 10 items of 95 documents
Mixed internal-external state approach for quantum computation with neutral atoms on atom chips
2006
We present a realistic proposal for the storage and processing of quantum information with cold Rb atoms on atom chips. The qubit states are stored in hyperfine atomic levels with long coherence time, and two-qubit quantum phase gates are realized using the motional states of the atoms. Two-photon Raman transitions are used to transfer the qubit information from the internal to the external degree of freedom. The quantum phase gate is realized in a double-well potential created by slowly varying dc currents in the atom chip wires. Using realistic values for all experimental parameters (currents, magnetic fields, ...) we obtain high gate fidelities (above 99.9%) in short operation times (~ 1…
Time-optimal control of the purification of a qubit in contact with a structured environment
2019
We investigate the time-optimal control of the purification of a qubit interacting with a structured environment, consisting of a strongly coupled two-level defect in interaction with a thermal bath. On the basis of a geometric analysis, we show for weak and strong interaction strengths that the optimal control strategy corresponds to a qubit in resonance with the reservoir mode. We investigate under which conditions qubit coherence and correlation between the qubit and the environment can speed up the control process.
Anatomy of spin–orbit torques
2017
The use of time-resolved X-ray microscopy allows a direct visualization of the magnetization switching for nanomagnets under the effect of spin–orbit torques.
Switching synchronization in one-dimensional memristive networks: An exact solution.
2017
We study a switching synchronization phenomenon taking place in one-dimensional memristive networks when the memristors switch from the high- to low-resistance state. It is assumed that the distributions of threshold voltages and switching rates of memristors are arbitrary. Using the Laplace transform, a set of nonlinear equations describing the memristors dynamics is solved exactly, without any approximations. The time dependencies of memristances are found, and it is shown that the voltage falls across memristors are proportional to their threshold voltages. A compact expression for the network switching time is derived.
Stability and Chaotic Attractors of Memristor-Based Circuit with a Line of Equilibria
2019
This report investigates the stability problem of memristive systems with a line of equilibria on the example of SBT memristor-based Wien-bridge circuit. For the considered system, conditions of local and global partial stability are obtained, and chaotic dynamics is studied. peerReviewed
Design of MOS Current Mode Logic Gates – Computing the Limits of Voltage Swing and Bias Current
2005
Minimizing a quality metric for an MCML gate, such as power-delay product or energy-delay product, requires solving a system of nonlinear equations subject to constraints on both bias current and voltage swing. In this paper, we will show that the limits of the swing and the bias current are affected by the constraints on maximum area and maximum delay. Moreover, methods for computing such limits are presented.
Quantum mechanical settings inspired by RLC circuits
2018
In some recent papers several authors used electronic circuits to construct loss and gain systems. This is particularly interesting in the context of PT-quantum mechanics, where this kind of effects appears quite naturally. The electronic circuits used so far are simple, but not so much. Surprisingly enough, a rather trivial RLC circuit can be analyzed with the same perspective and it produces a variety of unexpected results, both from a mathematical and on a physical side. In this paper we show that this circuit produces two biorthogonal bases associated to the Liouville matrix $\Lc$ used in the treatment of its dynamics, with a biorthogonality which is linked to the value of the parameter…
A Design Methodology for Low-Power MCML Ring Oscillators
2007
In this paper, a low-power design method for MCML based ring oscillators is presented. The proposed method takes into account the parasitic capacitances of the MOS transistors. To validate it, some ring oscillators with different oscillation frequencies were designed in a 0.18 mum CMOS technology. SPICE simulations demonstrate the effectiveness of the design method.
Modeling Networks of Probabilistic Memristors in SPICE
2021
Efficient simulation of stochastic memristors and their networks requires novel modeling approaches. Utilizing a master equation to find occupation probabilities of network states is a recent major departure from typical memristor modeling [Chaos, solitons fractals 142, 110385 (2021)]. In the present article we show how to implement such master equations in SPICE – a general purpose circuit simulation program. In the case studies we simulate the dynamics of acdriven probabilistic binary and multi-state memristors, and dc-driven networks of probabilistic binary and multi-state memristors. Our SPICE results are in perfect agreement with known analytical solutions. Examples of LTspice code are…
Protecting entanglement by adjusting the velocities of moving qubits inside non-Markovian environments
2017
Efficient entanglement preservation in open quantum systems is a crucial scope towards a reliable exploitation of quantum resources. We address this issue by studying how two-qubit entanglement dynamically behaves when two atom qubits move inside two separated identical cavities. The moving qubits independently interact with their respective cavity. As a main general result, we find that under resonant qubit-cavity interaction the initial entanglement between two moving qubits remains closer to its initial value as time passes compared to the case of stationary qubits. In particular, we show that the initial entanglement can be strongly protected from decay by suitably adjusting the velocit…