### 62772 results for qubit oscillator frequency

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: 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: Singh, Mandip

Date: 2014-07-01

**flux**-**qubit**-cantilever interrupted by a single Josephson junction is...flux-**qubit**-cantilever corresponds to a quantum entanglement between magnetic...**oscillation** ω i i.e. the **frequency** in absence of magnetic field. The external...**frequency** ( E / h ) is ∼ 4 × 10 11 Hz....**frequency** ( E / h ) is ∼ 3.9 × 10 11 Hz....**oscillator** is introduced that consists of a flux **qubit** in the form of ...**flux** **qubit** with a single Josephson junction is considered throughout this...**oscillates** about an equilibrium angle θ 0 with an intrinsic **frequency** ...flux-**qubit**-cantilever. A part of the flux **qubit** (larger loop) is in the... the **flux**-**qubit**-cantilever to its ground state....**qubit** and the mechanical degrees of freedom of the cantilever are naturally...**oscillation** **frequencies**, consider a flux-**qubit**-cantilever made of niobium...**flux**-**qubit**-cantilever shown in Fig. fig1 where a part of a superconducting...**frequencies** of the flux-**qubit**-cantilever are ω X ≃ 2 π × 7.99 × 10 10 ...**qubit** and the cantilever. An additional magnetic flux threading a DC-SQUID...**qubit** in the form of a cantilever. The magnetic flux linked to the flux...**qubit**...**frequencies** are ω φ ≃ 2 π × 7.99 × 10 10 rad/s, ω δ = 2 π × 22384.5 ...**flux** **qubit** forms a cantilever. The larger loop is interrupted by a smaller ... In this paper a macroscopic quantum **oscillator** is introduced that consists of a flux **qubit** in the form of a cantilever. The magnetic flux linked to the flux **qubit** and the mechanical degrees of freedom of the cantilever are naturally coupled. The coupling is controlled through an external magnetic field. The ground state of the introduced flux-**qubit**-cantilever corresponds to a quantum entanglement between magnetic flux and the cantilever displacement.

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Contributors: Oxtoby, Neil P., Gambetta, Jay, Wiseman, H. M.

Date: 2007-06-24

**qubit**, is used to damp a classical oscillator circuit. The resulting realistic...**frequency** (rf) weak measurements where a low-transparency quantum point... the **qubit** electron, denoted by E 1 and E 0 for the near and far dot, ...low-**frequency** (dc) weak measurements. In this paper we extend realistic...**oscillator** circuit to be a QPC (see Fig. fig:dqdqpc for details). Measurement...**qubit**. A schematic of the isolated DQD and capacitively coupled QPC is...**qubit**. The charge basis states are denoted | 0 and | 1 (see Fig. fig:...**qubit** coupled to a classical L C **oscillator** with inductance L and capacitance...**qubits** is important for quantum computation, particularly for the purposes...radio-**frequency** point contact), with two benefits over the SET — lower...**qubit** using a radio-frequency quantum point contact including experimental...**frequency** is the same as the signal of interest (or very slightly detuned...**qubit**. The rf+dc mode of operation is considered. Here the QPC is biased...charge **qubit** coupled to a classical L C oscillator with inductance L and...**qubit**, is used to damp a classical **oscillator** circuit. The resulting realistic... **qubit** coupled to a classical L C oscillator with inductance L and capacitance...low-**frequency** beats due to mixing the signal with the LO are easily detected...charge-**qubit** detector, that may nevertheless be higher than the dc-QPC...**qubit** and capacitively coupled low-transparency QPC between source (S)...**oscillator**, L O , and then measured. fig:rfcircuit...**oscillator** (relative to the QPC), where the **oscillator** slaves to the **qubit**... **qubit**. The charge basis states are denoted | 0 and | 1 (see Fig. fig ... The extension of quantum trajectory theory to incorporate realistic imperfections in the measurement of solid-state **qubits** is important for quantum computation, particularly for the purposes of state preparation and error-correction as well as for readout of computations. Previously this has been achieved for low-**frequency** (dc) weak measurements. In this paper we extend realistic quantum trajectory theory to include radio **frequency** (rf) weak measurements where a low-transparency quantum point contact (QPC), coupled to a charge **qubit**, is used to damp a classical **oscillator** circuit. The resulting realistic quantum trajectory equation must be solved numerically. We present an analytical result for the limit of large dissipation within the **oscillator** (relative to the QPC), where the **oscillator** slaves to the **qubit**. The rf+dc mode of operation is considered. Here the QPC is biased (dc) as well as subjected to a small-amplitude sinusoidal carrier signal (rf). The rf+dc QPC is shown to be a low-efficiency charge-**qubit** detector, that may nevertheless be higher than the dc-QPC (which is subject to 1/f noise).

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Contributors: Fedorov, Kirill G., Shcherbakova, Anastasia V., Schäfer, Roland, Ustinov, Alexey V.

Date: 2013-01-22

flux qubit....through** the **qubit corresponds to** the **changing of** the **persistent currents i...embracing a flux qubit, as shown in Fig. AJJ+Qubit. The current induced...the** flux** qubit with a coupling loop (yellow loop) and control line (green...**frequency** versus magnetic flux through the **qubit** corresponds to the changing... the qubit corresponds to** the **changing of** the **persistent currents in the...**oscillations**, we have performed systematic measurements of the dependence...**frequency** deviation from equilibrium δ ν / ν 0 of the fluxon **oscillation**...**qubit** as a current dipole to the annular junction, we detect periodic ...the** flux** qubit loop....the flux qubit....**oscillation** **frequency** from the unperturbed case δ ν = ν μ - ν 0 , where...**qubit**...**qubit**, **qubit** readout...**qubit**. The time delay of the fluxon can be detected as a **frequency** shift...**oscillation** **frequency** due to the coupling to the flux **qubit**. Every point...current in** the **flux qubit. Thus, the persistent current in** the **qubit manifests...flux qubit. Every point consists of 100 averages. Bias current was set...**frequency** versus bias current. Black line shows the result of perturbation...**oscillation** **frequency** for μ = 0 . Black line in Fig. FD shows the dependence...flux qubit versus magnetic frustration (black line). Red line shows the...**qubits** by using ballistic Josephson vortices are reported. We measured...**qubit**. We found that the scattering of a fluxon on a current dipole can...**oscillation** **frequency** versus magnetic flux through the **qubit**. We found...**qubit** loop....**qubit**. ... Experiments towards realizing a readout of superconducting **qubits** by using ballistic Josephson vortices are reported. We measured the microwave radiation induced by a fluxon moving in an annular Josephson junction. By coupling a flux **qubit** as a current dipole to the annular junction, we detect periodic variations of the fluxon's **oscillation** **frequency** versus magnetic flux through the **qubit**. We found that the scattering of a fluxon on a current dipole can lead to the acceleration of a fluxon regardless of a dipole polarity. We use the perturbation theory and numerical simulations of the perturbed sine-Gordon equation to analyze our results.

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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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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: Greenberg, Ya. S., Izmalkov, A., Grajcar, M., Il'ichev, E., Krech, W., Meyer, H. -G.

Date: 2002-08-07

**oscillations** in a phase **qubit**. The external source, typically in GHz range...**qubit** levels. The resulting Rabi oscillations of supercurrent in the **qubit**...**qubit**. According to the estimates for dephasing and relaxation times, ...**qubit**. The external source, typically in GHz range, induces transitions...**frequency** in MHz range....three-**junction** **qubit** in classical regime, when the hysteretic dependence...**qubit** in classical regime, when the hysteretic dependence of ground-state...**qubit**...**qubit** levels. The resulting Rabi **oscillations** of supercurrent in the **qubit**...**qubit**. Detailed calculation for zero and non-zero temperature are made...**qubit** coupled to a tank circuit....**oscillations** between quantum states in mesoscopic superconducting systems ... Time-domain observations of coherent **oscillations** between quantum states in mesoscopic superconducting systems were so far restricted to restoring the time-dependent probability distribution from the readout statistics. We propose a new 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**. Detailed calculation for zero and non-zero temperature are made for the case of persistent current **qubit**. According to the estimates for dephasing and relaxation times, the effect can be detected using conventional rf circuitry, with Rabi **frequency** in MHz range.

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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

**oscillator**. We achieve generation and control of the entangled state by...**frequencies** are shown by the filled squares in b). b, Rabi **frequency**, .......**oscillations**: after a π pulse on the **qubit** resonance ( | 00 → | 10 ) we...flux **qubit** (the smallest loop closed by three junctions); the **qubit** to...**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** symmetry point Δ = 5.9 GHz. a, Switching probability as a function...**oscillator**, as demonstrated in ion/atom-trap experiments or cavity quantum...**qubit** (a two-level system) and a superconducting quantum interference ...**qubits**. Single-**qubit** operations, direct coupling between two **qubits**, and... the **qubit** transition. In the upper scan, the system is first excited ...through the **qubit** area away from the **qubit** symmetry point. Inset, energy...**qubit** coupled to a harmonic oscillator...Qub ... 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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Contributors: Catelani, G., Schoelkopf, R. J., Devoret, M. H., Glazman, L. I.

Date: 2011-06-04

**qubit**, such as the transmon and phase **qubits**. We start with the the semiclassical...**ϕ** ̂ / 2 qubit-quasiparticle coupling in Eq. ( HTle) has a striking effect...**qubit** controlled by a magnetic flux, see Eq. ( Hphi). (b) Effective circuit...**qubit** biased at Φ e = Φ 0 / 2 with E J / E L = 10 . The horizontal lines...flux **qubit** biased at Φ e = Φ 0 / 2 with E J / E L = 10 . The horizontal...the flux qubit ground states | - and excited state | + are** the **lowest ...**qubit** sate. The results of Sec. sec:semi are valid for transitions between...**qubits**. The interaction of the **qubit** degree of freedom with the quasiparticles...**frequency** [cf. Eq. ( pl_fr)]...**qubit** frequency in the presence of quasiparticles....**frequency** is given by Eq. ( Gnn) with ϕ 0 = 0 and is independent of n ...**qubit** **frequency** in the presence of quasiparticles.... C , the qubit can be described by** the **effective circuit of Fig. fig1...**oscillations** of the energy levels are exponentially small, see Appendix...**qubit** resonant **frequency**. In the semiclassical regime of small E C , the... a **qubit** controlled by a magnetic flux, see Eq. ( Hphi). (b) Effective...**qubit** properties in devices such as the phase and flux **qubits**, the split...**the** **qubit** sate. The results of Sec. sec:semi are valid for transitions...**qubits**...**frequency** ω p , Eq. ( pl_fr)] and nearly degenerate levels whose energies...**qubit** decay rate induced by quasiparticles, and we study its dependence...**frequency** ω p , Eq. ( pl_fr), and give, for example, the rate Γ 1 0 . ...the flux quantum** the **qubit states | - , | + are respectively symmetric...anharmonic qubit, such as** the **transmon and **phase **qubits. We start with ... As low-loss non-linear elements, Josephson junctions are the building blocks of superconducting **qubits**. The interaction of the **qubit** degree of freedom with the quasiparticles tunneling through the junction represent an intrinsic relaxation mechanism. We develop a general theory for the **qubit** decay rate induced by quasiparticles, and we study its dependence on the magnetic flux used to tune the **qubit** properties in devices such as the phase and flux **qubits**, the split transmon, and the fluxonium. Our estimates for the decay rate apply to both thermal equilibrium and non-equilibrium quasiparticles. We propose measuring the rate in a split transmon to obtain information on the possible non-equilibrium quasiparticle distribution. We also derive expressions for the shift in **qubit** **frequency** in the presence of quasiparticles.

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