### 63157 results for qubit oscillator frequency

Contributors: Strauch, F. W., Dutta, S. K., Paik, Hanhee, Palomaki, T. A., Mitra, K., Cooper, B. K., Lewis, R. M., Anderson, J. R., Dragt, A. J., Lobb, C. J.

Date: 2007-03-02

**frequency**, and two-photon Rabi **frequency** are compared to measurements ...**frequency** Ω R , 01 of the one-photon 0 1 transition as function of microwave...**qubit**, scanned in **frequency** (vertical) and bias current (horizontal). ...**qubit** (current-biased Josephson junction) at high microwave drive power...**qubit** with Nb/AlOx/Nb tunnel junctions. Good agreement is found between...**oscillations** of the escape rate for I a c = 16.5 nA....**oscillations** have been observed in many superconducting devices, and represent...**oscillation** **frequency** Ω ̄ R , 01 as a function of the level spacing ω ...**qubit**...**qubits**) in a quantum computer. We use a three-level multiphoton analysis...phase qubit, scanned in frequency (vertical) and bias current (horizontal ... Rabi **oscillations** have been observed in many superconducting devices, and represent prototypical logic operations for quantum bits (**qubits**) in a quantum computer. We use a three-level multiphoton analysis to understand the behavior of the superconducting phase **qubit** (current-biased Josephson junction) at high microwave drive power. Analytical and numerical results for the ac Stark shift, single-photon Rabi **frequency**, and two-photon Rabi **frequency** are compared to measurements made on a dc SQUID phase **qubit** with Nb/AlOx/Nb tunnel junctions. Good agreement is found between theory and experiment.

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

Date: 2007-05-12

the **qubit**, and I q t the current circulating in the **qubit**. The persistent...**phase** **qubit** (Fig. 2 in ). The dependence of the frequency of these oscillations...**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** (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**...in the **qubit** circuit produces a magnetic moment, which is measured by ...**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 ...**oscillations** is in the different scale of the resonance **frequency**. To ...and the **qubit**, and I q t the current circulating in the **qubit**. The persistent...a **phase** **qubit** (Fig. 2 in ). The dependence of the frequency of these ... 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: Averin, D. V.

Date: 2002-02-05

**qubit**, σ z and σ y , as required in the QND Hamiltonian ( 2). For discussion...**oscillations** avoiding the detector-induced dephasing that affects the ... **qubit**. The oscillations are represented as a spin rotation in the z -...**frequency** Δ . QND measurement is realized if the measurement frame (dashed...**qubit** structure that enables measurements of the two non-commuting observables...**oscillations** in an individual two-state system. Such a measurement enables...**frequency** Ω ≃ Δ ....**qubits** which combine flux and charge dynamics....**qubit**...**oscillations** of a **qubit**. The **oscillations** are represented as a spin rotation ... The concept of quantum nondemolition (QND) measurement is extended to coherent **oscillations** in an individual two-state system. Such a measurement enables direct observation of intrinsic spectrum of these **oscillations** avoiding the detector-induced dephasing that affects the standard (non-QND) measurements. The suggested scheme can be realized in Josephson-junction **qubits** which combine flux and charge dynamics.

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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: Whittaker, J. D., da Silva, F. C. S., Allman, M. S., Lecocq, F., Cicak, K., Sirois, A. J., Teufel, J. D., Aumentado, J., Simmonds, R. W.

Date: 2014-08-08

i n ≈ 4 , qubit lifetimes are relatively large across** the **full qubit ...**Qubits**...**oscillations** for **frequencies** near f 01 = 7.38 GHz. (b) Line-cut on-resonance...**qubit** anharmonicity, **qubit**-cavity coupling and detuning. A tunable cavity...a) Relative **qubit** anharmonicity** α r **versus **qubit** frequency ω 01 / 2 π ...is** the **qubit junction critical current, with** the **phase difference across the...**qubit** anharmonicity α r versus **qubit** **frequency** ω 01 / 2 π (design A )....**qubit** inductively coupled to a single-mode, resonant cavity with a tunable...minima....QB...**qubit** **frequency** change both Δ 01 and the ** qubit’s** anharmonicity α . In ...

**qubit**far detuned, biased at its maximum

**frequency**. The solid line is ...

**qubit**and cavity

**frequencies**and the dashed lines show the new coupled...

**qubits**....

**qubit**

**frequency**, at f 01 = 7.98 GHz, Ramsey

**oscillations**gave T 2 * = ...

**qubit**-cavity system, we show that dynamic control over the cavity

**frequency**...measure of the

**qubit**anharmonicity as shown later in Fig. Fig9....

**phase**

**qubit**(design A ) remains stable enough for operation (see text)...

**qubit**

**frequencies**. In order to capture the maximum dispersive

**frequency**...

**qubit**, and residual bus coupling for a system with multiple

**qubits**. With...

**qubit**evolutions and optimize state readout during

**qubit**measurements....

**frequency**of f c m a x = 7.07 GHz while sweeping the

**qubit**flux bias ...

**oscillation**decay time of T ' = 409 ns. (c) Ramsey

**oscillations**versus...

**oscillations**gave T ' = 727 ns, a separate measurement of

**qubit**energy...the

**qubit**flux bias is swept. Two different data sets (with the

**qubit**... GHz while sweeping

**the**qubit flux bias φ q . In

**both**cases, when the ...

**frequency**provides a way to strongly vary both the

**qubit**-cavity detuning...cavity (

**qubit**) (see text)....

**frequency**that allows for both microwave readout of tunneling and dispersive...resultant flux coupling of

**the**qubit bias coil, M q

**B**= 10.9 pH. The ... We describe a tunable-cavity QED architecture with an rf SQUID phase

**qubit**inductively coupled to a single-mode, resonant cavity with a tunable

**frequency**that allows for both microwave readout of tunneling and dispersive measurements of the

**qubit**. Dispersive measurement is well characterized by a three-level model, strongly dependent on

**qubit**anharmonicity,

**qubit**-cavity coupling and detuning. A tunable cavity

**frequency**provides a way to strongly vary both the

**qubit**-cavity detuning and coupling strength, which can reduce Purcell losses, cavity-induced dephasing of the

**qubit**, and residual bus coupling for a system with multiple

**qubits**. With our

**qubit**-cavity system, we show that dynamic control over the cavity

**frequency**enables one to avoid Purcell losses during coherent

**qubit**evolutions and optimize state readout during

**qubit**measurements. The maximum

**qubit**decay time $T_1$ = 1.5 $\mu$s is found to be limited by surface dielectric losses from a design geometry similar to planar transmon

**qubits**.

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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....**oscillation** of the retrapping probability in one of the wells has a **frequency**...**qubit**. In the phase regime, the manipulation of the energy states is realized...phase qubit....**oscillation** **frequency** versus the normalized amplitude of the microwave...**qubit**, where the coherent evolution between the two flux states is induced... phase qubit by applying microwave pulses at 19 GHz. The oscillation frequency...**frequency** of the Larmor **oscillations**, the microwave-free **qubit** manipulation...**oscillation** and microwave-driven Rabi **oscillation** are rather similar. ...**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: Serban, I., Solano, E., Wilhelm, F. K.

Date: 2007-02-28

between qubit and oscillator. Here ℏ Ω / k B T = 2 , κ / Ω = 0.025 and... seen by the qubit. The dephasing rate is also expected to diverge. The...**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...through the qubit loop is Φ q and through the SQUID is Φ S .... of a qubit with one Josephson junction (phase γ , capacitance C q and...**qubit** quadratically coupled to its detector, a damped harmonic **oscillator**...effect after the qubit and the oscillator become entangled. The dephasing...**qubit** and **oscillator**. We also show that the pointer becomes measurable...states of the qubit split already during the transient motion of p ̂ t...**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...different qubit states (c). Here ℏ Ω / k B T = 2 , Δ / Ω = 0.45 , κ / ... we later approximate the qubit as a two-level system. The qubit used ...**qubits**...**oscillator** has the **frequency** Ω because it has not yet "seen" the **qubit**...about the qubit state, and has the advantage of avoiding decoeherence ... 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: Eugene Grichuk, Margarita Kuzmina, Eduard Manykin

Date: 2010-09-26

**qubit** simulates the behavior of electric field of
polarized light beam...**qubit** model has been designed as a
stochastic **oscillator** formed by a pair...**qubits** that is
exploited as a computation resource in one-way quantum
...**oscillators** is
proposed for modeling of a cluster of entangled **qubits** ...**oscillators** with chaotically modulated limit cycle radii and
**frequencies**...one-**qubit**
gates are suggested. Changing of cluster entanglement degree...**qubit** cluster, is designed, and system of equations for
network dynamics...**oscillators**...**qubit** model has been designed as a
stochastic oscillator formed by a pair ... A network of coupled stochastic **oscillators** is
proposed for modeling of a cluster of entangled **qubits** that is
exploited as a computation resource in one-way quantum
computation schemes. A **qubit** model has been designed as a
stochastic **oscillator** formed by a pair of coupled limit cycle
**oscillators** with chaotically modulated limit cycle radii and
**frequencies**. The **qubit** simulates the behavior of electric field of
polarized light beam and adequately imitates the states of two-level
quantum system. A cluster of entangled **qubits** can be associated
with a beam of polarized light, light polarization degree being
directly related to cluster entanglement degree. Oscillatory network,
imitating **qubit** cluster, is designed, and system of equations for
network dynamics has been written. The constructions of one-**qubit**
gates are suggested. Changing of cluster entanglement degree caused
by measurements can be exactly calculated.

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Contributors: Ginossar, Eran, Bishop, Lev S., Girvin, S. M.

Date: 2012-07-19

**qubit** state measurement in circuit quantum electrodynamics...**qubit** and cavity are on resonance or far off-resonance (dispersive)....superconducting transmon qubits...**frequency** and amplitude. The region of bifurcation...**oscillator** with its set of transition **frequencies** depending on the state...**qubit** and cavity are strongly coupled. We focus on the parameter ranges...**qubit** decay** . **T 1** . **has** . **distinct influence on** the **lifetime of** the **QCS...**qubit** quantum state discrimination and we present initial results for ...**frequency**).... 4 transmon qubits transmonat 7.0** . **7.5** . **8.0** . **12.3** . **H z** . **All qubits...**oscillator**...**qubits** in the circuit quantum electrodynamics architecture, where the ...**oscillator** and we analyze the quantum and semi-classical dynamics. One...**oscillator** (Duffing **oscillator**) Duffing **oscillator**, constructed by making... the **qubit** is detuned from** the **cavity** . **ω q** . **ω c** . **2 π** . **2 g ). It is...disruptive to the **qubit** state and it is realized where** the **cavity and ... **qubit** (Fig. gino:chirp_figure). This selective dynamical mapping of** th**...**frequency**. For (b), if the state of one (‘spectator’) **qubit** is held constant...**frequency** response bifurcates, and the JC **oscillator** enters a region of...**frequency** and amplitude. Despite the presence of 4 **qubits** in the device...one **qubit**, see Fig. gino:fig:return. Such an asymmetric **qubit** dependent...**qubit** **frequency**. (c) Wave packet snapshots at selected times (indicated...anharmonic transmon....the **qubit** being detuned. Due to the interaction with the **qubit**, the cavity...**frequency** of panel (b) conditioned on the initial state of the **qubit**. ...**qubit** state q : (a) for the JC model, parameters as in Figs. gino:fig ... In this book chapter we analyze the high excitation nonlinear response of the Jaynes-Cummings model in quantum optics when the **qubit** and cavity are strongly coupled. We focus on the parameter ranges appropriate for transmon **qubits** in the circuit quantum electrodynamics architecture, where the system behaves essentially as a nonlinear quantum **oscillator** and we analyze the quantum and semi-classical dynamics. One of the central motivations is that under strong excitation tones, the nonlinear response can lead to **qubit** quantum state discrimination and we present initial results for the cases when the **qubit** and cavity are on resonance or far off-resonance (dispersive).

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Contributors: Lisenfeld, Juergen, Mueller, Clemens, Cole, Jared H., Bushev, Pavel, Lukashenko, Alexander, Shnirman, Alexander, Ustinov, Alexey V.

Date: 2009-09-18

**frequencies**. Each trace was recorded after adjusting the **qubit** bias to...**frequency** while the **qubit** was kept detuned. A π pulse was applied to measure...**qubit**-fluctuator system...the **qubit** in the excited state, P t , vs. driving frequency; (b) Fourier-transform...phase **qubit** circuit. (b) Probability to measure the excited **qubit** state...**the** **qubit** was kept detuned. A π pulse was applied to measure **the** energy...**oscillations**
...**qubits** often show signatures of coherent coupling to microscopic two-level...**frequency** of 7.805 GHz (indicated by a dashed line)....**qubits**, Josephson junctions, two-level
fluctuators, microwave spectroscopy...**qubit** and fluctuator v ⊥ and to the microwave field Ω q and Ω f v ....**qubit** in the excited state, P t , vs. driving **frequency**; (b) Fourier-transform...**qubit** levels....**qubit** as and and those of the TLF as and . Arrows indicate the couplings...** qubit’s** Rabi

**frequency**Ω q / h is set to 48 MHz....

**qubit**, in which we induce Rabi oscillations by resonant microwave driving...

**oscillations**observed experimentally....

**frequency**, revealing the coupling to a two-level defect state having a...

**the**

**qubit**loop. The

**qubit**state is controlled by an externally applied...levels

**in**

**the**

**qubit**....

**qubit**, in which we induce Rabi

**oscillations**by resonant microwave driving...

**qubit**is tuned close to the resonance with an individual TLF and the Rabi...

**frequency**components.

**Frequency**and visibility of each component depend...

**qubit**relative to the TLF’s resonance

**frequency**, which is indicated in...

**qubit**transition. In this work, we studied

**the**

**qubit**interacting with ...

**qubit**above or below the fluctuator's level-splitting. Theoretical analysis...

**qubit**circuit. (b) Probability to measure the excited

**qubit**state (color-coded...

**qubit**-TLF coupling), interesting 4-level dynamics are observed. The experimental...

**frequency**of order of the

**qubit**-TLF coupling), interesting 4-level dynamics...in the

**qubit**. (As the anharmonicity Δ / h ∼ 100 MHz in our circuit is...

**the**phase

**qubit**circuit (

**the**

**qubit**subspace) and disregard

**the**longitudinal ... Superconducting

**qubits**often show signatures of coherent coupling to microscopic two-level fluctuators (TLFs), which manifest themselves as avoided level crossings in spectroscopic data. In this work we study a phase

**qubit**, in which we induce Rabi

**oscillations**by resonant microwave driving. When the

**qubit**is tuned close to the resonance with an individual TLF and the Rabi driving is strong enough (Rabi

**frequency**of order of the

**qubit**-TLF coupling), interesting 4-level dynamics are observed. The experimental data shows a clear asymmetry between biasing the

**qubit**above or below the fluctuator's level-splitting. Theoretical analysis indicates that this asymmetry is due to an effective coupling of the TLF to the external microwave field induced by the higher

**qubit**levels.

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