Entangled Systems: New Directions In Quantum Physics. Quantum Physics Who Already Know The Fundamentals, Audretsch’s “Entangled . File Type: PDF . as every virtual system must be booted up. It is suggested that If two quantum particles are “entangled”, what happens to one instantly affects the other, even if . creation could be simply when the system was booted up. . travels faster than light but one entangled quantum entity instantly affects the other anywhere.

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However, the qubits in the two models have different decoherence The parameters are the same as in Fig. The decoherence and relaxation eystems the qubit in SIB model Using the numerical path integral method we investigate the decoherence and relaxation of qubits in spin-boson SB and spin-intermediate harmonic oscillator IHO -bath SIB models.

The cases that the environment baths with low and medium frequencies are investigated. It is shown that the qubits in SB and SIB models have the same decoherence and syshems as the baths with low frequencies. However, the qubits in the two models have different decoherence and relaxation as the baths with medium frequencies.

Here, we suppose the oscillation frequencies of the Using the numerical path integral method we investigate the decoherence and relaxation of syxtems coupled to an Ohmic bath directly and via an intermediate harmonic oscillator IHO.

When we choose suitable parameters the qubits in the two models may have almost same decoherence and relaxation times. However, the decoherence and relaxation times of the qubit in the qubit -IHO-bath model can be modulated through changing the coupling coefficients of the qubit -IHO and IHO-bath and the oscillation frequency of the IHO.

The net magnetic flux threading An additional magnetic flux threading A part of the flux -qubit larger loop is projected A part of the flux- qubit larger loop is projected In this paper a macroscopic quantum oscillator is proposed, which consists of a flux- qubit in the form of a cantilever.

The net magnetic flux threading through fuletype flux- qubit and the mechanical degrees of freedom of the cantilever are naturally coupled. The coupling between the cantilever and the magnetic flux is controlled through an external magnetic field. The ground state of the flux- qubit -cantilever turns out to be an auretsch quantum state, where the cantilever deflection and the magnetic flux are the entangled degrees of freedom.

A variant, which is a special case of the flux- qubit -cantilever without a Josephson junction, is also discussed. Starting in the ground state We show that for a qubit coupled to one oscillatorLandau—Zener LZ sweep of a qubit coupled to two oscillators. A qubit may undergo Landau—Zener transitions due to its coupling to one or eentangled quantum harmonic oscillators. We show that for a qubit coupled to one oscillatorLandau—Zener transitions can be used for single-photon generation and for the controllable creation of qubit — oscillator entanglement, with state-of-the-art circuit QED as a promising realization.

Moreover, for a qubit coupled to two cavities, we show that Landau—Zener sweeps of the qubit are well suited for the robust creation of entangled cavity states, in particular symmetric Bell states, with the qubit acting as the entanglement mediator.

At the heart of our proposals lies the calculation of the exact Landau—Zener transition probability for the qubitby summing all orders of the corresponding series in time-dependent perturbation theory.

Audrftsch transition probability emerges to be independent of the oscillator frequenciesaudrrtsch inside and outside the regime where a rotating-wave approximation is valid.

## Entangled Systems: New Directions in Quantum Physics

We propose a method for characterising the energy level structure of a solid state qubit by monitoring the noise level in its environment. We consider a model persistent current qubit in a lossy reservoir and demonstrate that the noise in a classical bias field is a sensitive function of the applied field.

In both cases, the experimental data Black bars denote Cooper pair boxes. Each qubit is based on a Cooper pair box connected to a reservoir In both cases, the experimental data open We have analyzed and measured the quantum coherent dynamics of a circuit containing two-coupled superconducting charge qubits.

Each qubit is based on a Cooper pair box connected to a reservoir electrode through a Josephson junction.

Two qubits are coupled electrostatically by a small island overlapping both Cooper pair boxes. Quantum state manipulation of the entanbled circuit is done by applying non-adiabatic voltage pulses to the common gate.

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We read out each qubit by means of probe electrodes connected to Cooper pair boxes through high-Ohmic tunnel junctions. With ssytems a setup, the measured pulse-induced probe currents are proportional to the probability for each qubit to have an extra Cooper pair after the manipulation. As expected from theory and observed experimentally, the measured pulse-induced current in each probe has two frequency components whose position on the frequency axis can be externally controlled. Our simulations show that in the absence of decoherence and with a rectangular pulse shape, the system remains entangled most of the time reaching maximally entangled states at certain instances.

We discuss an experimental proposal on quantum feedback control of a double-dot qubitwhich seems to be within filegype reach of the present-day technology. Similar to the earlier proposal, the feedback loop is used to maintain the coherent oscillations in the qubit for an ciletype long time; however, this is done in a significantly simpler way.

The main idea is to use systwms quadrature components of the noisy detector current to monitor approximately the phase of qubit oscillations. The correlated oscillation is shown We couple the Rabi oscillation in a double quantum dot DQD with the quantum tunneling in another DQD by Coulomb interaction between the neighboring dots. The correlated oscillation is shown clearly in the tunneling current.

Audetsch then, a single optical signal accomplishes a gang control of two electrons. This result encourages superior design of two- qubit quantum gates based on correlated DQDs. The accumulation of information The scheme is based We present a new scheme to detect and visualize oscillations of a single quantum system in real time.

Entagnled scheme is based upon a sequence of very weak generalized measurements, distinguished by their low disturbance and low information gain. Accumulating the information from the single measurements by means of an appropriate Bayesian estimator, the actual oscillations can be monitored nevertheless with high accuracy and low disturbance. For this purpose only the minimum and the maximum expected oscillation frequency need to be known.

The accumulation of information is based on a general derivation of the optimal estimator of the expectation value of a Hermitian observable for a sequence of measurements. At any time it takes into account all the preceding measurement results.

### Entangled Systems: New Directions in Quantum Physics – Free eBooks Download

It is almost zero in the time interval The frequency of the beats Quantum computing requires a set of universal quantum gates. It flips the audretscj of the target qubit conditioned on the state of the control qubit.

We investigated the possibility of implementing a CNOT logic gate using magnetically coupled impurity spins of diamond, namely the electron spin-1 carried by the nitrogen-vacancy color center and the electron spin carried by a nearby nitrogen atom in substitutional position P1 center. It is shown that a 96ns gate time with a high-fidelity can be realized by means of pulsed electron spin resonance spectroscopy.

Filters Reset Filter Results. Klee, Thomas Konrad Date: Image 5 Tabular Data.