1,690 research outputs found
Quantum State Sensitivity of an Autoresonant Superconducting Circuit
When a frequency chirped excitation is applied to a classical high-Q
nonlinear oscillator, its motion becomes dynamically synchronized to the drive
and large oscillation amplitude is observed, provided the drive strength
exceeds the critical threshold for autoresonance. We demonstrate that when such
an oscillator is strongly coupled to a quantized superconducting qubit, both
the effective nonlinearity and the threshold become a non-trivial function of
the qubit-oscillator detuning. Moreover, the autoresonant threshold is
sensitive to the quantum state of the qubit and may be used to realize a high
fidelity, latching readout whose speed is not limited by the oscillator Q.Comment: 5 pages, 4 figure
Cavity-assisted quantum bath engineering
We demonstrate quantum bath engineering for a superconducting artificial atom
coupled to a microwave cavity. By tailoring the spectrum of microwave photon
shot noise in the cavity, we create a dissipative environment that autonomously
relaxes the atom to an arbitrarily specified coherent superposition of the
ground and excited states. In the presence of background thermal excitations,
this mechanism increases the state purity and effectively cools the dressed
atom state to a low temperature
1/f noise of Josephson-junction-embedded microwave resonators at single photon energies and millikelvin temperatures
We present measurements of 1/f frequency noise in both linear and
Josephson-junction-embedded superconducting aluminum resonators in the low
power, low temperature regime - typical operating conditions for
superconducting qubits. The addition of the Josephson junction does not result
in additional frequency noise, thereby placing an upper limit for fractional
critical current fluctuations of (Hz) at 1 Hz for
sub-micron, shadow evaporated junctions. These values imply a minimum dephasing
time for a superconducting qubit due to critical current noise of 40 -- 1400
s depending on qubit architecture. Occasionally, at temperatures above 50
mK, we observe the activation of individual fluctuators which increase the
level of noise significantly and exhibit Lorentzian spectra
Complexes of manganese(III) oxychlorosulphate with some nitrogen bases
717-718Manganese(III) oxychlorosulphate complexes of the type MnOSO3.Cl.L2 and MnOSO3Cl.L’ with monodentate (aniline, biphenyl amine, acetonitrile, pyridine, 3-amino-2-chloropyridine, 4-cyanopyridine, acridine) and bidentate ligands (2,2-bipyridyl and 1,10-phenanthroline) have been characterized on the basis of their elemental analysis, molar conductance, magnetic susceptibility measurements, infrared and electronic spectral data. These studies, corroborate the tridentate nature and lowering of C3v symmetry of the chlorosulphate group. The com lexes are of high-spin octahedral type as evidenced by agnetic moment values and electronic spectral bands
Transition Metal Complexes of a-Naphthylamine Dithiocarbamate
a-Naphthylamine dithiocarbamate and its complexes with
Co(II), Ni(U), Cu(II), Ru(III) , Rh(III), Pd(II), Pt(IV), Zn(II), Cd(II)
and Hg(II) have been prepared and characterized by chemical
analysis, IR - and reflectance spectral studies and magnetic
susceptibili ty measurements. In all these complexes the dithiocarbamato
moiety acts as a chelate. The Ni(II), Cu(II) and Pd(Il)
complexes have been found to be square planar while those of
Ru(III), Rh(III) and Pt(IV) were proposed to be octahedral in
nature. The Co(II) ion seems to have a tetrahedral geometry, unlike
the other known square planar dithiocarbamato complexes of
Co(II). No definite structure, however, could be proposed for Zn(II),
Cd(II) and Hg(II) on the basis of limited studies
Pentacoordinated Ti(IV) Chloride & Sn(IV) Bromide & Iodide Complexes with Acridine & Piperazine
209-21
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