### 25677 results for qubit oscillator frequency

Contributors: Xian-Ting Liang

Date: 2008-09-03

**qubits** in spin-boson (SB) and spin-intermediate harmonic oscillator (IHO...**frequencies**. However, the **qubits** in the two models have different decoherence...**frequency** ω of the bath modes, where Δ=5×109Hz,λκ=1,ξ=0.01,Ω0=10Δ,T=0.01K...**qubit**-IHO and IHO-bath and the oscillation frequency of the IHO....**frequencies** for the two cases are taken according to Fig. 2.
...low-**frequency** bath. The parameters are the same as in Fig. 1.
...**qubit** in SIB model can be modulated through changing the coupling coefficients...**qubits** in the two models have different decoherence and relaxation as ...high-**frequency** baths.
...**qubits** in spin-boson (SB) and spin-intermediate harmonic **oscillator** (IHO...**qubits** coupled to low- and medium-frequency Ohmic baths directly and via...**frequencies** are investigated. It is shown that the **qubits** in SB and SIB...**frequencies**. The decoherence and relaxation of the **qubit** in SIB model ...**frequencies** and effective bath in (b) low and (d) medium **frequencies**. ...**qubit**-IHO and IHO-bath and the **oscillation** **frequency** of the IHO....**qubits** in SB and SIB models have the same decoherence and relaxation as ... 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 relaxation as the baths with low **frequencies**. However, the **qubits** in the two models have different decoherence and relaxation as the baths with medium **frequencies**. The decoherence and relaxation of the **qubit** in SIB model can be modulated through changing the coupling coefficients of the **qubit**-IHO and IHO-bath and the **oscillation** **frequency** of the IHO.

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Contributors: Xian-Ting Liang

Date: 2007-12-05

lower-**frequency** and high-**frequency** cut-off of the baths modes ω0=11Δ, ...**qubits** coupled to an Ohmic bath directly and via an intermediate harmonic...**qubit** **in** the **qubit**-**IHO**-bath model can be modulated through changing the...**in** the two models may have almost same decoherence and relaxation times...**qubits** in the two models may have almost same decoherence and relaxation...**qubit**-**IHO** and **IHO**-bath and the oscillation frequency of the **IHO**....**oscillator** (IHO). Here, we suppose the **oscillation** **frequencies** of the ...**qubit**-IHO and IHO-bath and the **oscillation** **frequency** of the IHO....**qubit** in the **qubit**-IHO-bath model can be modulated through changing the...**qubit** coupled to an Ohmic bath directly and via an intermediate harmonic ... Using the numerical path integral method we investigate the decoherence and relaxation of **qubits** coupled to an Ohmic bath directly and via an intermediate harmonic **oscillator** (IHO). Here, we suppose the **oscillation** **frequencies** of the bath modes are higher than the IHO’s. 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.

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Contributors: Mandip Singh

Date: 2015-07-14

flux-**qubit** in the form of a cantilever. The net magnetic flux threading...superconducting-loop-**oscillator** when the intrinsic **frequency** is 10 kHz...flux-**qubit** and the mechanical degrees of freedom of the cantilever are...flux-**qubit**-cantilever turns out to be an entangled quantum state, where...superconducting-loop-**oscillator** with its axis of rotation along the z-axis... flux-qubit and the cantilever. An additional magnetic** flux** threading ...**frequency** (E/h) is ∼4×1011 Hz.
... flux-qubit-cantilever. A part of the** flux**-qubit (larger loop) is projected...**oscillator** is proposed, which consists of a flux-**qubit** in the form of ...flux-**qubit**-cantilever without a Josephson junction, is also discussed....flux-**qubit**-cantilever. A part of the flux-**qubit** (larger loop) is projected...**qubit**...**frequency** (E/h) is ∼3.9×1011 Hz.
... 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 the 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 entangled 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.

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Contributors: Martijn Wubs, Sigmund Kohler, Peter Hänggi

Date: 2007-10-01

**qubit** may undergo Landau–Zener transitions due to its coupling to one ...a qubit coupled to two oscillators. Parameters: γ=0.25ℏv and Ω2=100ℏv,...**qubit**–oscillator entanglement, with state-of-the-art circuit QED as a ...**qubit** are well suited for the robust creation of entangled cavity states...**qubit** that is coupled to one **oscillator**. Starting in the ground state ...**qubit** coupled to one **oscillator**, far outside the RWA regime: γ=ℏΩ=0.25ℏv...**qubit** coupled to two cavities, we show that Landau–Zener sweeps of the...**oscillator** **frequencies**, both inside and outside the regime where a rotating-wave...**qubit** coupled to two **oscillators**. Parameters: γ=0.25ℏv, ℏΩ1=90ℏv, and ...case** the **qubit would be measured |↑〉.
...**oscillators**. We show that for a **qubit** coupled to one **oscillator**, Landau–Zener... the qubit–oscillator coupling γ. Parameters: γ=0.25ℏv and ℏΩ2=100ℏv, ...**qubit** coupled to one oscillator, Landau–Zener transitions can be used ...**oscillator** if the **qubit** would be measured in state |↓〉; the dash-dotted...**qubit** coupled to two **oscillators** with degenerate energies. Parameters:...**sweep** of a qubit coupled to two oscillators with degenerate energies. ...**qubit**–**oscillator** entanglement, with state-of-the-art circuit QED as a ...LZ **sweep** of a qubit coupled to two oscillators. Parameters: γ=0.25ℏv, ... A **qubit** may undergo Landau–Zener transitions due to its coupling to one or several quantum harmonic **oscillators**. We show that for a **qubit** coupled to one **oscillator**, Landau–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 **qubit**, by summing all orders of the corresponding series in time-dependent perturbation theory. This transition probability emerges to be independent of the **oscillator** **frequencies**, both inside and outside the regime where a rotating-wave approximation is valid.

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Contributors: J.F. Ralph, T.D. Clark, M.J. Everitt, H. Prance, P. Stiffell, R.J. Prance

Date: 2003-10-20

**qubit** in a lossy reservoir and demonstrate that the noise in a classical...**qubit** by monitoring the noise level in its environment. We consider a ...**qubit** via environmental noise...**qubit** [6] inductively coupled to a (low **frequency**) classical **oscillator**...**frequency** **oscillator** at the resonance point (Φdc=0.00015Φ0) for the three...**qubit**...**frequency** **oscillator** at 300 MHz, as a function of the static magnetic ... 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.

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Contributors: Yu.A. Pashkin, T. Yamamoto, O. Astafiev, Y. Nakamura, D.V. Averin, T. Tilma, F. Nori, J.S. Tsai

Date: 2005-01-01

**oscillation** **frequencies** of both **qubits** in the case of zero coupling (Em...of both qubits in the case of zero coupling (Em=0).
... each qubit, indicated by arrow. In both cases, the experimental data ...second (b) qubit when the system is driven non-adiabatically to the points...inter-**qubit** coupling which is also responsible for the avoided level crossing...the second (b) qubit when the system is driven non-adiabatically to the...**qubit** to have an extra Cooper pair after the manipulation. As expected...**frequency** components whose position on the **frequency** axis can be externally...**qubit** circuit is done by applying non-adiabatic voltage pulses to the ...two-coupled-qubit circuit. Black bars denote Cooper pair boxes.
...**oscillations** in the first (a) and the second (b) **qubit** when the system...**qubits**. Each **qubit** is based on a Cooper pair box connected to a reservoir...**qubits** are coupled electrostatically by a small island overlapping both...**qubits**...**qubit** by means of probe electrodes connected to Cooper pair boxes through...two-coupled-**qubit** circuit. Black bars denote Cooper pair boxes.
...**qubit**, indicated by arrow. 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 **qubit** circuit is done by applying non-adiabatic voltage pulses to the common gate. We read out each **qubit** by means of probe electrodes connected to Cooper pair boxes through high-Ohmic tunnel junctions. With such 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. This is a result of the inter-**qubit** coupling which is also responsible for the avoided level crossing that we observed in the **qubits**’ spectra. 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.

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Contributors: Alexander N. Korotkov

Date: 2005-03-01

**qubit**, which seems to be within the reach of the present-day technology...**qubit** **oscillations**....**qubit** oscillations....**qubit** for an arbitrary long time; however, this is done in a significantly...**qubit**...**oscillations** in the **qubit** for an arbitrary long time; however, this is...**frequency** mismatch (Ω≠Ω0).
... We discuss an experimental proposal on quantum feedback control of a double-dot **qubit**, which seems to be within the 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 arbitrary long time; however, this is done in a significantly simpler way. The main idea is to use the quadrature components of the noisy detector current to monitor approximately the phase of **qubit** **oscillations**.

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Contributors: Weidong Xie, Bingxin Chu, Suqing Duan, Yan Xie, Weidong Chu, Ning Yang, Xian-Geng Zhao

Date: 2015-08-01

**oscillation** with the same ΩR in each case is shown in gray line.
...**oscillation** in a double quantum dot (DQD) with the quantum tunneling in...**oscillating** electron and the quantum tunneling one, and gives a tendency...two-**qubit** quantum gates based on correlated DQDs....**frequency** ΩR and tunneling rate Tc. The correlated **oscillation** is shown...**frequency** ΩR and tunneling rate Tc at t=tp (a), t=1.25tp (b), t=1.5tp ...**oscillation** and the quantum tunneling reach their strongest correlation...**oscillation**...**oscillation** and another one in quantum tunneling. (b) Time-average current ... 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. Such a coupling leads to correlation of the Rabi **oscillating** electron and the quantum tunneling one, and gives a tendency of synchronizing them under appropriate Rabi **frequency** ΩR and tunneling rate Tc. The correlated **oscillation** is shown clearly in the tunneling current. As ΩR=Tc, the Rabi **oscillation** and the quantum tunneling reach their strongest correlation and the two electrons finish their complete transitions simultaneously. And 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.

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Contributors: Jürgen Audretsch, Felix E. Klee, Thomas Konrad

Date: 2007-01-29

**frequency** ΩR of the undisturbed Rabi **oscillations**.
...**oscillations** can be monitored nevertheless with high accuracy and low ...**qubit's** Rabi oscillations and processed measurement signal for p¯=0.5,...**oscillation** **frequency** need to be known. The accumulation of information...**qubit's** Rabi **oscillations** and processed measurement signal for p¯=0.5,...**oscillations** of a single quantum system in real time. The scheme is based ... We present a new scheme to detect and visualize **oscillations** of a single quantum system in real time. The 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.

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Contributors: M. Hebbache

Date: 2014-01-01

**qubit** up: red, blue and green lines represent, respectively, |A′|2, |B...**qubit**) gates and the controlled-NOT (CNOT) which is the analog of the ...**oscillates** at the low **frequency** χ. It is almost zero in the time interval...**qubit** down: blue, red and green lines correspond, respectively, to the... two-**qubit** CNOT gate irradiated by a sequence of two microwave π/2-pulses...**qubit** conditioned on the state of the control **qubit**. We investigated the...two-**qubit** CNOT gate irradiated by a sequence of two microwave π/2-pulses...**oscillations**. Control **qubit** down: blue, red and green lines correspond...**oscillates** at the high **frequency** D (=2.88GHz). The **frequency** of the beats ... Quantum computing requires a set of universal quantum gates. The standard set includes single quantum bit (**qubit**) gates and the controlled-NOT (CNOT) which is the analog of the classical XOR gate. It flips the state 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-12 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.

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