### 63089 results for qubit oscillator frequency

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: Il'ichev, E., Oukhanski, N., Izmalkov, A., Wagner, Th., Grajcar, M., Meyer, H. -G., Smirnov, A. Yu., Brink, Alec Maassen van den, Amin, M. H. S., Zagoskin, A. M.

Date: 2003-03-20

**Qubit**...**oscillations**.... ℏ , the** **qubit** **is** **effectively** **decoupled** **from** **the** **tank** **unless** **it** **oscillates...**frequency** ω T . That is, while wide-band (i.e., fast on the **qubit** time...**qubit**, coupled to a high-quality tank circuit tuned to the Rabi **frequency**...**oscillations** in time. We report evidence for such **oscillations** in a _continuously...flux **qubit** is inductively coupled to a tank circuit. The DC source applies...**qubit** is effectively decoupled from the tank unless it **oscillates** with...the **qubit** through a separate coil at a frequency close to the level separation...**qubit** **frequency**, confirm that the effect is due to Rabi **oscillations**. ...**qubit**, coupled to a high-quality tank circuit tuned to the Rabi frequency...**frequency** of the tank is measured as a function of HF power.... the **qubit** increasing the tank’s linewidth ; these are inconsequential...The** **qubit** **was** **fabricated** **out** **of** **Al** **inside** **the** **tank’s** **pickup** **coil (Fig....**qubit** modifying the tank’s inductance and hence its central **frequency**,...**qubit** through a separate coil at a **frequency** close to the level separation... the** **potential** **profile** **of** **a** **3JJ** **qubit** **in** **the** **classical** **regime ....**qubit** inside the Nb pancake coil....**qubit** quality factor \~7000.... irradiated **qubit** modifying the tank’s inductance and hence its central... in** **the** **qubit, and** **simultaneously** **as** **a** **filter** **protecting** **it** **from** **noise... 3** **nF. The** **qubit** **has** **L** **q = 24** **pH; the** **larger** **junctions** **have** **C** **q = 3.9 ... Under resonant irradiation, a quantum system can undergo coherent (Rabi) **oscillations** in time. We report evidence for such **oscillations** in a _continuously_ observed three-Josephson-junction flux **qubit**, coupled to a high-quality tank circuit tuned to the Rabi **frequency**. In addition to simplicity, this method of_Rabi spectroscopy_ enabled a long coherence time of about 2.5 microseconds, corresponding to an effective **qubit** quality factor \~7000.

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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...**qubit** in different conditions (different **oscillation** **frequencies**) by changing...**frequency** noise contributions, and discuss the experimental results and...**qubit** manipulation, changing the potential from the two-well “W” case ...**qubit**, indicated as double SQUID **qubit**, can be manipulated by rapidly ...**qubit** manipulated by fast pulses: experimental observation of distinct...**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...used** for **the qubit manipulation, changing the potential from the two-well...**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: 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: 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: 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: 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: 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: Yoshihara, Fumiki, Nakamura, Yasunobu, Yan, Fei, Gustavsson, Simon, Bylander, Jonas, Oliver, William D., Tsai, Jaw-Shen

Date: 2014-02-06

**oscillation**, $1/f$ noise...parallel to the qubit’s energy eigenbasis; this component is not averaged...**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...

**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...

**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...

**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 ...

**qubit**by studying the decay of Rabi oscillations under strong driving ...the qubit followed by a readout pulse, and P s w as a function of the ...to the qubit followed by a readout pulse, and P s w as a function of the... qubit by a mutual inductance of 1.2 pH and nominally cooled to 35 mK....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: Liberti, G., Zaffino, R. L., Piperno, F., Plastina, F.

Date: 2005-11-21

**qubit** is coupled to a single **oscillator** mode. 99 weiss U. Weiss, Quantum...**frequency** and the level asymmetry of the **qubit**. This is done in the adiabatic...**qubit**. This is done in the adiabatic regime in which the time evolution...of a qubit with an ohmic environment was numerically analyzed. It turns...of the **qubit** tunnelling amplitude D . One can appreciate that the result...**oscillator** in the lower adiabatic potential, for D = 10 and α = 2 and ...**qubit** is much faster than the oscillator one. Within the adiabatic approximation...**oscillator** defined in Eq. ( due1), centered in Q = ± Q 0 , respectively...**qubit** ( W = D = 0 ) would have given a pair of independent parabolas instead...the qubit is coupled to a single oscillator mode....**qubit** tunnelling amplitude D . One can appreciate that the result of Eq...**qubit** strongly interacting with an oscillator mode, as a function of the...asymmetry in the qubit Hamiltonian. As mentioned in section sect2 above...**qubit** coupled to a resonator in the adiabatic regime...**qubit** and the environmental **oscillator**. Unfortunately, the coupling strength...to the reduced qubit state. For example, for a large enough interaction...**oscillator** localizes in one of the wells of its effective potential and...**qubit** is much faster than the **oscillator** one. Within the adiabatic approximation...the qubit and the environmental oscillator. Unfortunately, the coupling...**qubit** strongly interacting with an **oscillator** mode, as a function of the ... We discuss the ground state entanglement of a bi-partite system, composed by a **qubit** strongly interacting with an **oscillator** mode, as a function of the coupling strenght, the transition **frequency** and the level asymmetry of the **qubit**. This is done in the adiabatic regime in which the time evolution of the **qubit** is much faster than the **oscillator** one. Within the adiabatic approximation, we obtain a complete characterization of the ground state properties of the system and of its entanglement content.

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