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  • Qubit dynamics in Bloch ball picture. North pole corresponds to the excited (antisymmetric) energy eigenstate |1〉 and south pole corresponds to the ground (symmetric) state |0〉. Initially the electron is localized in one of the dots. Quality of Rabi oscillations Q=40. The effect of image charge potential: (a) K=0 and (b) K=0.4. ... Quality of qubit Rabi oscillations vs. distance to a metal surface. Centers of quantum dots are located 100nm apart. Lines and points correspond to analytical and numerical solutions, respectively. ... Quality of qubit Rabi oscillations vs. the distance between quantum dots. Qubit is located 50nm far from the metal surface. Lines and points correspond to analytical and numerical solutions, respectively. ... The moving charge in the qubit drags charges in metal that indispensably entails Joule loss: d is a double dot separation and D is a distance to the metal surface.
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  • Illustration of a linear ion trap including an axial magnetic field gradient. The static field makes individual ions distinguishable in frequency space by Zeeman-shifting their internal energy levels (solid horizontal lines represent qubit states). In addition, it mediates the coupling between internal and external degrees of freedom when a driving field is applied (dashed horizontal lines stand for vibrational energy levels of the ion string, see text). ... Rabi oscillations on the optical E2 transition S1/2-D5/2 in Ba + . A fit of the data (solid line) yields a Rabi frequency of 71.4 × 2πkHz and a transversal relaxation time of 100 μs (determined by the coherence time of the ir light used to drive the E2 resonance). ... Illustration of the coupled system ‘qubit ⊗ harmonic oscillator’ in a trap with magnetic field gradient. Internal qubit transitions lead to a displacement dz of the ion from its initial equilibrium position and consequently to the excitation of vibrational motion. In the formal description the usual Lamb–Dicke parameter is replaced by a new effective one (see text). ... (a) Relevant energy levels and transitions in 138Ba + . (b) Schematic drawing of major experimental elements. OPO: Optical parametric oscillator; YAG: Nd:YAG laser; LD: laser diode; DSP: Digital signal processing system allows for real time control of experimental parameters; AOM: Acousto-optic modulators used as optical switches and for tuning of laser light; PM: Photo multiplier tube, serves for detection of resonance fluorescence. All lasers are frequency and intensity stabilized (not shown). ... Schematic drawing of the resonances of qubits j and j + 1 with some accompanying sideband resonances. The angular frequency vN corresponds to the Nth axial vibrational mode, and the frequency separation between carrier resonances is denoted by δω.
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  • Silicon beam: (a) instantaneous frequency; (b) instantaneous damping; (c) equivalent modal frequency; (d) equivalent modal damping. _______ primary vacuum; - - - - pressure ∼300 mbar; . . . . . pressure ∼600mbar; – · – · – atmospheric pressure. ... Quartz beam: (a) equivalent modal frequency; (b) equivalent modal damping. _______ primary vacuum; - - - - pressure ∼300mbar; . . . . . pressure ∼600mbar; – · – · – atmospheric pressure. ... (a) Identified modal frequency: quartz structure; (b) identified modal frequency: lithium niobate structure; (c) identified modal damping: quartz structure; (d) identified modal damping: lithium niobate structure; symbols: experimental values; lines: polynomial fitting. and _______ primary vacuum; ● and - - - - pressure ∼300 mbar; ▴ and . . . . . pressure ∼600mbar; ■ and – · – · – atmospheric pressure. ... Department of Physics and Metrology of Oscillator, FEMTO-ST Institute, 32 Avenue de l’Observatoire, 25044 Besançon, France... (a) Instantaneous frequency; (b) instantaneous damping; (c) equivalent modal frequency; (d) equivalent modal damping. _______ 0.2ms−1; - - - - 0.15ms−1; . . . . . 0.10ms−1. ... Lithium niobate beam: (a) equivalent modal frequency; (b) equivalent modal damping. _______ primary vacuum; - - - - pressure ∼300mbar; . . . . . pressure ∼600mbar; – · – · – atmospheric pressure.
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  • Qubits in solids... Schematic diagram of qubits addressed in a frequency domain. The ions whose 3H4(1)± 3 2–1D2(1) transitions are resonant with a common cavity mode are employed as qubits. ... Basic scheme of the concept of the frequency-domain quantum computer. The atoms are coupled to a single cavity mode. Lasers with frequencies of νk and νl are directed onto the set of atoms and interact with the kth and lth atoms selectively.
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  • The relational curve of the oscillating period T and the electron–LOP coupling constant α. ... Qubit... The relational curve of the oscillating period T and the confinement length R.
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  • The same as in Fig. 4 for U=2 and for the time-dependent energy levels ε1 and ε2 presented in the inset in the left panel—they oscillate harmonically with frequency ω=1 and the pulse envelope has a Gaussian shape of duration τ=30 centered at t0=100. ... The same as in Fig. 3 but for U=0 (upper panels) and for U=2 (lower panels) for the time-dependent energy levels ε1 and ε2 presented in the inset, in the upper left panel—they oscillate harmonically around the values ε=±1 with frequency ω=0.1, and the pulse envelope has a Gaussian shape of duration τ=30 centered at t0=92. The energy levels of the right qubit have constant values ε3=ε4=1. ... Coupled qubits... Occupancy probability n1(t=∞) of the first QD of the left qubit (qubits are in the perpendicular configuration) as a function of the frequency ω of the time-dependent V1(t) displayed in the inset—it oscillates harmonically with ω=0.5 and the pulse envelope has a Gaussian shape of duration τ=30, V2=1, U1=U2=2, εi=0, n1(0)=n3(0)=1. ... Occupation probability n1(t) of the first QD in the left qubit (the left panel) and n4(t) of the second QD in the right qubit (the right, panel) as the functions of time for U=10. The energy levels ε1 and ε2 of the left qubit oscillate harmonically around the values ε=±2 with amplitude Δ=2, frequency ω=0.05 (in V/ℏ units, see the inset in the left panel) and energy levels of the right qubit having constant values, ε3=−ε4=2. The qubits are in the linear configuration. ... Schematic representation of two interacting qubits formed by two DQDs with one excess electron in each qubit. The broken lines correspond to the Coulomb interaction U between the electrons localized on the neighboring QDs of both qubits and V denotes the interdot tunneling matrix element. ... Charge oscillations
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  • In all plots the decay rates κ/g=0.1, γr/g=4.35×10-2, and cavity factor Q=1400. The quantum dot excitonic Bohr frequency is assumed to be in resonance with the cavity field frequency, i.e., ωqd=ωc. The amplitude of the external laser field to the cavity decay rate ratio is fixed to I/κ=631. The coherence ρ01≡ρ(0,1) dynamics is plotted for: (a) Δωcl=0.4g; (b) Δωcl=g; (c) Δωcl=100g; (d) Δωcl=1000g. The cavity photons mean number is plotted in (e) and (f). We have used a logarithmic scale for the time axis and the values: (i) Δωcl=g; (ii) Δωcl=1000g, for the solid and dotted curves, respectively. ... Rabi oscillations
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  • Detection and manipulation of the qubit. (a) Fluorescence image of nanodiamond prepared on the CPW transmission line. NV S1 is circled. The inset is a photo of CPW with 20μm gaps fabricated on a silica glass. (b) CW ODMR spectrum for NV S1. The inset is energy levels of NV center. A 532nm laser is used to excite and initialize the NV center. Fluorescence is collected by a confocal microscope. (c) Rabi oscillation of NV S1. Rabi oscillation period is about 62ns. (d) Hahn echo and CPMG control pulse sequences. πx (πy) implies the direction of microwave magnetic fields parallel to x (y). ... Spectral density of the spin bath. (a) NV S1, (b) NV S2. All values of spectral density S(ω) of the spin bath are extracted from the CPMG data (blue points). Each blue data point represents a specific probed frequency ω=πn/t, in which n is the number of control pulses and t is the specific duration. The red points are the average values at a certain frequency. The mean spectral density is fit to the Lorentzian function (Eq. (3)) (green line). (For interpretation of the references to color in this figure caption, the reader is referred to the web version of this article.) ... Characterization of lifetime of NV center spins. (a) Ramsey interference of NV S1 (circle) and NV S2 (diamond). The oscillation in Ramsey signal originates from the beating among different transitions corresponding to the host three 14N nuclear spin states. The oscillation frequency of Ramsey signal is equal to microwave detuning from spin resonance. Solid lines ~exp[−(t/T2⁎)m] fit the experimental data points, where m is a free parameter. (b) Comparison of Hahn echo coherence time T2 of NV S1 (circle) and NV S2 (diamond). The solid lines are fits to ~exp[−(t/T2)p], in which p is a fit parameter.
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  • Voltage controlled oscillator... Microwave Communication and Radio Frequency Integrated Circuit Lab, Department and Institute of Electronic Engineering, National Yunlin University of Science and Technology, 123 University Road, Section 3, Douliou 64002, Yunlin, Taiwan, ROC... Output oscillation frequency versus control voltage of (a) chip1 VCO. (b) chip2 VCO.
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  • Average PTO power as a function of oscillating frequency for straight (♦: solid line) and bent leg (□: broken line) tines (oscillation angle β=+27°). ... Subsoiler draft signals with time for the control and the range of oscillating frequencies. ... Dominant frequency of draft signal over the oscillating frequency range. ... Proportion of cycle time for cutting and compaction phases versus oscillating frequency (oscillation angle β=+27°). ... Dominant frequency of torque signal over the oscillating frequency range. ... Frequency... Oscillating tine
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