Effects of charge noise on a pulse-gated singlet-tripletS−T−qubit

Abstract

We study the dynamics of a pulse-gated semiconductor double quantum dot qubit. In our experiments, the qubit coherence times are relatively long, but the visibility of the quantum oscillations is low. We show that these observations are consistent with a theory that incorporates decoherence arising from charge noise that gives rise to detuning fluctuations of the double dot. Because effects from charge noise are largest near the singlet-triplet avoided level crossing, the visibility of the oscillations are low when the singlet-triplet avoided level crossing occurs in the vicinity of the charge degeneracy point crossed during the manipulation, but there is only modest dephasing at the large detuning value at which the quantum phase accumulates. This theory agrees well with experimental data and predicts that the visibility can be increased greatly by appropriate tuning of the interdot tunneling rate.

Observation of Ultrabroadband Acoustic Focusing Based on V‐Shaped Meta‐Atoms

“…[23][24][25][26][27][28][29][30] Additionally, due to the features of planner structure and subwavelength thickness, acoustic metasurfaces [31][32][33][34][35] have provided the possibility to design ultrathin and easily integrated focusing lenses. Different from other mechanisms, the focusing effect of this type of lens is attributed to phase manipulation, in which the lens is designed by an array of phased unit cells, such as the coiling-up structures, [31,36,37] labyrinthine structures, [32,38,39] and Helmholtz resonators. [40][41][42][43] However, the phase manipulation of these focusing lenses is realized by adjusting the parameters of each unit cell, and thus the working bandwidth of the designed lenses is generally narrow.…”

Nonequilibrium orbital transitions via applied electrical current in calcium ruthenates

“…An abrupt AFM transition occurs only at a considerably lower Neel temperature TN =110 K [2,3], highlighting its close association with a further distorted crystal structure. Extensive investigations of this system have established that quantum effects are intimately coupled to external stimuli in general and extremely sensitive to lattice perturbations in particular [7,[13][14][15][16][17][18][19][20]].…”

“…In this work, we investigate structural, magnetic and transport properties as a function of electrical current and temperature in 3% Mn doped Ca2RuO4, and, for comparison, in pure Ca2RuO4 and 9% Mn doped Ca2RuO4. It is emphasized that the dilute Mn doping for Ru preserves essential structural and physical properties of Ca2RuO4 but weakens the often pulverizing firstorder structural phase transition at 357 K, making the single crystals more robust to sustain thermal cycling needed for thorough measurements [19,20]. This work reveals that a novel coupling between small applied electrical current and the lattice critically reduces the orthorhombicity and the octahedral rotation that in turn precipitously suppress the AFM state and subsequently induce a new orbital order below 80 K at a current density > 0.15 A/cm2 in pure and Mn doped Ca2RuO4.…”

“…The single crystals are grown using floating-zone technique [20]. The lattice parameters are measured as functions of electrical current and temperature using both neutron and x-ray diffraction [25].…”

Physics‐Guided Data‐Mining Driven Design of Room‐Temperature Multiferroic Perovskite Oxides

“…It should be noted that ferroelectric spontaneous polarization emerges only when the acentric displacement is large enough to overcome the fluctuations, i.e., r > r 0 , one nonzero value (r 0 ) determined by the fluctuations. [7,8,35] Under this condition, the quadratic relationship between T C(FE) and descriptor of product of A/B radius ratio with reduced mass of unit cell showed in Figure 1 can be derived out from the empirical relationship of T C / r À r 0 ð Þ 2 , because those acentric displacements correlated with covalent bonding are able to minimize thermodynamic free energy of ferroelectric phase. Within such scenario, using tensile stresses and chemical pressure (Figure 2(a) and extended Figure S2, Supporting Information), ferroelectricity was ably induced emerging out in SrTiO 3 thin film, [36] SrTi 16…”