### 57529 results for qubit oscillator frequency

Contributors: unknown

Date: 2015-05-18

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

Date: 2011-10-07

**qubit** is only weakly sensitive to intrinsic noise. We find that this behaviour...**qubit** in different conditions (different oscillation frequencies) by changing...**oscillations** with eq. envelope. The blue line in the left panel is the...**oscillations** observed for different pulse height. The measured **frequency**...**oscillations** exhibiting non-exponential decay, indicating a non trivial...**oscillation** **frequencies** observed (about 10-20 GHz), corresponding to the...**qubit** in different conditions (different **oscillation** **frequencies**) by changing...**frequency** noise contributions, and discuss the experimental results and...**qubit**, indicated as double SQUID **qubit**, can be manipulated by rapidly ...**qubit** manipulation, changing the potential from the two-well “W” case ...**qubit** manipulated by fast pulses: experimental observation of distinct...**frequency** Ω / 2 π given by eq. omega for ϕ x = 0 as a function of ϕ c ... A particular superconducting quantum interference device (SQUID)**qubit**, indicated as double SQUID **qubit**, can be manipulated by rapidly modifying its potential with the application of fast flux pulses. In this system we observe coherent **oscillations** exhibiting non-exponential decay, indicating a non trivial decoherence mechanism. Moreover, by tuning the **qubit** in different conditions (different **oscillation** **frequencies**) by changing the pulse height, we observe a crossover between two distinct decoherence regimes and the existence of an "optimal" point where the **qubit** is only weakly sensitive to intrinsic noise. We find that this behaviour is in agreement with a model considering the decoherence caused essentially by low **frequency** noise contributions, and discuss the experimental results and possible issues.

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Contributors: Omelyanchouk, A. N., Shevchenko, S. N., Zagoskin, A. M., Il'ichev, E., Nori, Franco

Date: 2007-05-12

**oscillations**....**frequency** ω = 0.612 , and the decay rate γ = 10 -3 . Low-**frequency** classical...**oscillations** around a minimum of the potential profile of Fig. fig1 as...**frequency** ω . The main peak ( ω 0 ≈ 0.6 ) corresponds to the resonance...**qubit** circuit produces a magnetic moment, which is measured by the inductively...**qubit** (Fig. 2 in ). The dependence of the **frequency** of these **oscillations**...high-**frequency**) harmonic mode of the system, $\omega$. Like in the case...**qubits** in the classical regime...**frequency**, M the mutual inductance between the tank and the **qubit**, and...**qubit** in the _classical_ regime can produce low-frequency oscillations...**qubit** in the _classical_ regime can produce low-**frequency** **oscillations**...**oscillations** are clearly seen. (b) Low-**frequency** **oscillations** of the persistent...**oscillations**, the **frequency** of these pseudo-Rabi **oscillations** is much ...**frequency** $\omega$ and its subharmonics ($\omega/n$), but also at its ...**qubit** (Fig. 2 in ). The dependence of the frequency of these oscillations...**qubit**, and I q t the current circulating in the **qubit**. The persistent ...**oscillations** is in the different scale of the resonance **frequency**. To ... Nonlinear effects in mesoscopic devices can have both quantum and classical origins. We show that a three-Josephson-junction (3JJ) flux **qubit** in the _classical_ regime can produce low-**frequency** **oscillations** in the presence of an external field in resonance with the (high-**frequency**) harmonic mode of the system, $\omega$. Like in the case of_quantum_ Rabi **oscillations**, the **frequency** of these pseudo-Rabi **oscillations** is much smaller than $\omega$ and scales approximately linearly with the amplitude of the external field. This classical effect can be reliably distinguished from its quantum counterpart because it can be produced by the external perturbation not only at the resonance **frequency** $\omega$ and its subharmonics ($\omega/n$), but also at its overtones, $n\omega$.

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Contributors: Serban, I., Solano, E., Wilhelm, F. K.

Date: 2007-02-28

**qubit** initially in the state 1 / 2 | ↑ + | ↓ the probability distribution...**qubit**. The dephasing rate is also expected to diverge. The peaks at Ω ...**qubit** split already during the transient motion of p ̂ t , much faster...**qubit** has been lost....**qubit** and **oscillator** or between **oscillator** and bath, corrections of the...**qubit** and the oscillator by means of their full Floquet state master equations...**qubit** and **oscillator**. Here ℏ Ω / k B T = 2 , κ / Ω = 0.025 and ℏ ν / k...**qubit** quadratically coupled to its detector, a damped harmonic **oscillator**...**qubit** and oscillator. Here ℏ Ω / k B T = 2 , κ / Ω = 0.025 and ℏ ν / k...**qubit** and **oscillator**. We also show that the pointer becomes measurable...**qubit** drawn in the single junction version, the surrounding SQUID loop...**qubit** quadratically coupled to its detector, a damped harmonic oscillator...**qubit** with one Josephson junction (phase γ , capacitance C q and inductance...**qubit** and the **oscillator** by means of their full Floquet state master equations...**frequency** is at resonance with the harmonic **oscillator** — we have a continuum...**qubit** loop is Φ q and through the SQUID is Φ S ....**qubit** and oscillator. We also show that the pointer becomes measurable...**qubit** and the **oscillator** become entangled. The dephasing rate drops again...**frequencies** to the value obtained in the case without driving....**frequency** ν for different vales of κ ( Δ / Ω = 0.5 ). Here ℏ Ω / k B T...**qubit** states (c). Here ℏ Ω / k B T = 2 , Δ / Ω = 0.45 , κ / Ω = 0.025 ...**qubit** and explore several measurement protocols, which include a long-term...**qubit** as a two-level system. The **qubit** used in the actual experiment contains...**qubits**...**oscillator** has the **frequency** Ω because it has not yet "seen" the **qubit** ... Motivated by recent experiments, we study the dynamics of a **qubit** quadratically coupled to its detector, a damped harmonic **oscillator**. We use a complex-environment approach, explicitly describing the dynamics of the **qubit** and the **oscillator** by means of their full Floquet state master equations in phase-space. We investigate the backaction of the environment on the measured **qubit** and explore several measurement protocols, which include a long-term full read-out cycle as well as schemes based on short time transfer of information between **qubit** and **oscillator**. We also show that the pointer becomes measurable before all information in the **qubit** has been lost.

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Contributors: Poletto, S, Chiarello, F, Castellano, M G, Lisenfeld, J, Lukashenko, A, Carelli, P, Ustinov, A V

Date: 2009-10-23

**qubit** manipulation allows for much faster coherent operations....**qubit**. In the phase regime, the manipulation of the energy states is realized...**oscillation** of the retrapping probability in one of the wells has a **frequency**...**qubit**, where the coherent evolution between the two flux states is induced...**oscillation** **frequency** versus the normalized amplitude of the microwave...**frequency** of the Larmor **oscillations**, the microwave-free **qubit** manipulation...**oscillation** and microwave-driven Rabi **oscillation** are rather similar. ...**qubit** by applying microwave pulses at 19 GHz. The oscillation frequency...**oscillation** of the double SQUID manipulated as a phase **qubit** by applying...**oscillation** **frequency** changes from 540 MHz to 1.2 GHz by increasing the...**qubit**...**oscillation** **frequencies** versus amplitude of the short flux pulse (full...**qubit**. ... We report on two different manipulation procedures of a tunable rf SQUID. First, we operate this system as a flux **qubit**, where the coherent evolution between the two flux states is induced by a rapid change of the energy potential, turning it from a double well into a single well. The measured coherent Larmor-like **oscillation** of the retrapping probability in one of the wells has a **frequency** ranging from 6 to 20 GHz, with a theoretically expected upper limit of 40 GHz. Furthermore, here we also report a manipulation of the same device as a phase **qubit**. In the phase regime, the manipulation of the energy states is realized by applying a resonant microwave drive. In spite of the conceptual difference between these two manipulation procedures, the measured decay times of Larmor **oscillation** and microwave-driven Rabi **oscillation** are rather similar. Due to the higher **frequency** of the Larmor **oscillations**, the microwave-free **qubit** manipulation allows for much faster coherent operations.

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Contributors: Yoshihara, Fumiki, Nakamura, Yasunobu, Yan, Fei, Gustavsson, Simon, Bylander, Jonas, Oliver, William D., Tsai, Jaw-Shen

Date: 2014-02-06

**oscillation**, $1/f$ noise...**oscillation** curves with different Rabi **frequencies** Ω R measured at different...** qubit’s** energy eigenbasis; this component is not averaged out when Ω R...

**frequency**δ ω (black open circles) and the Bloch–Siegert shift δ ω B S...

**qubit**'s level splitting of 4.8 GHz, a regime where the rotating-wave approximation...

**oscillations**due to quasistatic flux noise. “Optimal" in the last column...

**qubit**’s energy eigenbasis; this component is not averaged out when Ω R...

**oscillation**measurements, a microwave pulse is applied to the

**qubit**followed...

**oscillation**decay at ε = 0 , where the quasistatic noise contribution ...

**qubit**noise spectroscopy using Rabi oscillations under strong driving ...

**qubit**and its strong inductive coupling to a microwave line enabled high-amplitude...

**frequency**of ω m w / 2 π = 6.1 GHz, has a minimum of approximately ω ...

**frequency**range decreases with increasing

**frequency**up to 300 MHz, where...

**qubit**followed by a readout pulse, and P s w as a function of the microwave...

**frequencies**up to 1.7 GHz were achieved, approaching the

**qubit**'s level...

**frequency**Ω R 0 at the shifted resonance decreases as ε increases, while...

**qubit**by studying the decay of Rabi oscillations under strong driving ...

**frequency**, and cal: Γ R s t δ ω m w stands for the calculation to study...

**oscillations**under strong driving conditions. The large anharmonicity ...high-

**frequency**flux noise spectrum in a superconducting flux

**qubit**by ...

**qubit**by a mutual inductance of 1.2 pH and nominally cooled to 35 mK. ... We infer the high-

**frequency**flux noise spectrum in a superconducting flux

**qubit**by studying the decay of Rabi

**oscillations**under strong driving conditions. The large anharmonicity of the

**qubit**and its strong inductive coupling to a microwave line enabled high-amplitude driving without causing significant additional decoherence. Rabi

**frequencies**up to 1.7 GHz were achieved, approaching the

**qubit**'s level splitting of 4.8 GHz, a regime where the rotating-wave approximation breaks down as a model for the driven dynamics. The spectral density of flux noise observed in the wide

**frequency**range decreases with increasing

**frequency**up to 300 MHz, where the spectral density is not very far from the extrapolation of the 1/f spectrum obtained from the free-induction-decay measurements. We discuss a possible origin of the flux noise due to surface electron spins.

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Contributors: Beaudoin, Félix, da Silva, Marcus P., Dutton, Zachary, Blais, Alexandre

Date: 2012-08-09

**qubits** have **frequencies** separated enough that they do not overlap during...**qubit**-resonator or **qubit**-**qubit** spectrum. They are typically ver...**frequency** associated to the operating point φ i . This **frequency** is illustrated...two-**qubit** operations in circuit QED. ϵ is the strength of the drive used...**qubit**. The fidelity is extracted by injecting these unitaries in Eq. (...**qubit**-**qubit** entangled states. The parameters of every pulses entering ...**qubit** relaxation and dephasing is similar....**qubit**-resonator and **qubit**-**qubit** interactions. We discuss in detail how...**qubit** (see Section sec:SB)....**qubits** and microwave resonators. Up to now, these transitions have been...**qubit** or the resonator, with the significant disadvantage that such implementations...**qubit** frequency using a flux-bias line. Not only can first-order transitions...**oscillations** have been seen to be especially large for big relevant ε ...**oscillations** of the **qubit** **frequency** using a flux-bias line. Not only can...**oscillator** with **frequency** ω r = 7.8 GHz. As explained in Section sec:...**qubit** at the red sideband **frequency** assuming the second **qubit** is in its...**oscillations** in the Rabi **oscillations** that reduce the fidelity. These ...**qubit** transition **frequencies** in and out of resonance without crossing ...**qubit** frequency modulation...**oscillators** (see Section sec:Duffing) with E J 1 = 25 GHz, E J 2 = 35...**qubit** at the red sideband frequency assuming the second **qubit** is in its...**qubit** is excited. Blue dashed line: population transfer error 1 - P t ...**qubits** have frequencies separated enough that they do not overlap during...**qubit** splitting is modulated at a **frequency** that lies exactly between ... Sideband transitions have been shown to generate controllable interaction between superconducting **qubits** and microwave resonators. Up to now, these transitions have been implemented with voltage drives on the **qubit** or the resonator, with the significant disadvantage that such implementations only lead to second-order sideband transitions. Here we propose an approach to achieve first-order sideband transitions by relying on controlled **oscillations** of the **qubit** **frequency** using a flux-bias line. Not only can first-order transitions be significantly faster, but the same technique can be employed to implement other tunable **qubit**-resonator and **qubit**-**qubit** interactions. We discuss in detail how such first-order sideband transitions can be used to implement a high fidelity controlled-NOT operation between two transmons coupled to the same resonator.

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Contributors: Greenberg, Ya. S.

Date: 2003-03-04

**oscillations** in a phase **qubit**. The external source, typically in GHz range...**qubit** states, nevertheless the voltage across the tank **oscillates** with...**qubit**). We explicitly account for the back action of a tank circuit and...**oscillations** with lower **frequency**. Deterministic case (a) together with...**qubit** levels. The resulting Rabi **oscillations** of supercurrent in the **qubit**...**qubit** coupled to a dissipative tank circuit Q T = 100 , λ = 2.5 × 10 -...**qubit** to microscopic degrees of freedom in the solid. Fortunately this...**qubit**. The external source, typically in GHz range, induces transitions...**qubit** coupled to a dissipative tank circuit. The voltage across the tank...**oscillates** with a high **frequency** which is about 10 GHz in our case. As...**qubit** loop. As is seen from the Fig. fig4a, A **oscillates** with Rabi **frequency**...**oscillating** with Rabi **frequency**, while B (C) decays to zero. (Note: to...**qubit** coupled to a tank circuit....**qubit** levels. The resulting Rabi oscillations of supercurrent in the **qubit**...**qubit**. Computer simulations...**oscillations** correspond to Rabi **frequency**....**oscillates** with gap **frequency**, while the **frequency** of A is almost ten ...**qubit** evolution as the coupling between the **qubit** and the tank is increased...**qubit** coupled to a loss-free tank circuit. **Oscillations** of A. Deterministic...**qubit** as having definite wave function. However, if the interaction is...**qubit** without dissipation....**qubit** coupled to a loss-free tank circuit. Oscillations of A. Deterministic...**frequency**. Deterministic case (a) together with one realization (b) are...**oscillations** in MHz range can be detected using conventional NMR pulse...**qubit**. Here we present the results of detailed computer simulations of...**oscillations** between quantum states in mesoscopic superconducting systems ... Time-domain observations of coherent **oscillations** between quantum states in mesoscopic superconducting systems have so far been restricted to restoring the time-dependent probability distribution from the readout statistics. We propose a method for direct observation of Rabi **oscillations** in a phase **qubit**. The external source, typically in GHz range, induces transitions between the **qubit** levels. The resulting Rabi **oscillations** of supercurrent in the **qubit** loop are detected by a high quality resonant tank circuit, inductively coupled to the phase **qubit**. Here we present the results of detailed computer simulations of the interaction of a classical object (resonant tank circuit) with a quantum object (phase **qubit**). We explicitly account for the back action of a tank circuit and for the unpredictable nature of outcome of a single measurement. According to the results of our simulations the Rabi **oscillations** in MHz range can be detected using conventional NMR pulse Fourier technique.

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Contributors: Grajcar, M., Izmalkov, A., Il'ichev, E., Wagner, Th., Oukhanski, N., Huebner, U., May, T., Zhilyaev, I., Hoenig, H. E., Greenberg, Ya. S.

Date: 2003-03-31

**frequency** ω T . Then both amplitude v and phase shift χ (with respect...**qubit**, inductively coupled to a Nb LC tank circuit. The resonant properties...**qubit**, which changes drastically as its flux states pass through degeneracy...**oscillator** are sensitive to the effective susceptibility (or inductance...**qubit**’s quantum properties, without using spectroscopy. In a range 50 ...**qubit** states. Thus, the tank both applies the probing field to the **qubit**...**qubit** inductance by the tank flux, and (B) losses caused by field-induced...**frequency** due to the change of the effective **qubit** inductance by the tank...**qubit**...**qubit** vs external flux. The dashed lines represent the classical potential...**qubit**....**qubit** temperature at 30 mK. (c) Full dip width at half the maximum amplitude...**qubit** loop is inductively coupled to a parallel resonant tank circuit ...**qubit** coupled to a tank circuit. ... We have observed signatures of resonant tunneling in an Al three-junction **qubit**, inductively coupled to a Nb LC tank circuit. The resonant properties of the tank **oscillator** are sensitive to the effective susceptibility (or inductance) of the **qubit**, which changes drastically as its flux states pass through degeneracy. The tunneling amplitude is estimated from the data. We find good agreement with the theoretical predictions in the regime of their validity.

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Contributors: Chiorescu, I., Bertet, P., Semba, K., Nakamura, Y., Harmans, C. J. P. M., Mooij, J. E.

Date: 2004-07-30

**qubit**) junctions have a critical current of 4.2 (0.45) μ A. The device...**oscillator**. We achieve generation and control of the entangled state by...**Qubit** - SQUID device and spectroscopy a, Atomic force micrograph of the...**qubit** - oscillator system for some given bias point. The blue and red ...**qubit** area away from the **qubit** symmetry point. Inset, energy levels of...**frequencies** are shown by the filled squares in b). b, Rabi **frequency**, ...**oscillations**: after a π pulse on the **qubit** resonance ( | 00 → | 10 ) we...**frequencies** indicated by peaks in the SQUID switching probability when...**qubit** - **oscillator** system for some given bias point. The blue and red ...**oscillations** of the coupled system....**oscillations** at the **qubit** symmetry point Δ = 5.9 GHz. a, Switching probability...**qubit** (a two-level system) and a superconducting quantum interference ...**oscillator**, as demonstrated in ion/atom-trap experiments or cavity quantum...**qubit** (the smallest loop closed by three junctions); the **qubit** to SQUID...**qubits**. Single-**qubit** operations, direct coupling between two **qubits**, and...**qubit** coupled to a harmonic oscillator ... In the emerging field of quantum computation and quantum information, superconducting devices are promising candidates for the implementation of solid-state quantum bits or **qubits**. Single-**qubit** operations, direct coupling between two **qubits**, and the realization of a quantum gate have been reported. However, complex manipulation of entangled states - such as the coupling of a two-level system to a quantum harmonic **oscillator**, as demonstrated in ion/atom-trap experiments or cavity quantum electrodynamics - has yet to be achieved for superconducting devices. Here we demonstrate entanglement between a superconducting flux **qubit** (a two-level system) and a superconducting quantum interference device (SQUID). The latter provides the measurement system for detecting the quantum states; it is also an effective inductance that, in parallel with an external shunt capacitance, acts as a harmonic **oscillator**. We achieve generation and control of the entangled state by performing microwave spectroscopy and detecting the resultant Rabi **oscillations** of the coupled system.

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