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NWA 6356: unequilibrated polymict ureilite
Polymict ureilite NWA 6356 has not suffered an intensive metamorphism and keeps the evidence of multistage carbon injections, reducing sulphuric metasomatism, and consists of feldspathic clasts and best preserved CM-like chondrite fragments
Nonadiabatic quantum control of a semiconductor charge qubit
We demonstrate multipulse quantum control of a single electron charge qubit.
The qubit is manipulated by applying nonadiabatic voltage pulses to a surface
depletion gate and readout is achieved using a quantum point contact charge
sensor. We observe Ramsey fringes in the excited state occupation in response
to a pi/2 - pi/2 pulse sequence and extract T2* ~ 60 ps away from the charge
degeneracy point. Simulations suggest these results may be extended to
implement a charge-echo by reducing the interdot tunnel coupling and pulse rise
time, thereby increasing the nonadiabaticity of the pulses.Comment: Related papers at http://pettagroup.princeton.ed
The PYRIN Connection: Novel Players in Innate Immunity and Inflammation
Periodic fever syndromes (PFSs) comprise a subset of the hereditary autoinflammatory disorders that are defined by recurrent self-resolving attacks of systemic inflammatory reactions in the absence of infection or autoimmunity. Recent advances have led to the discovery that members of a new family of genes, the PYRIN family, account for several hereditary PFSs. Here we discuss new insights into the function of PYRIN proteins and the molecular basis of PFSs
Threshold Dynamics of a Semiconductor Single Atom Maser
We demonstrate a single-atom maser consisting of a semiconductor double
quantum dot (DQD) that is embedded in a high quality factor microwave cavity. A
finite bias drives the DQD out of equilibrium, resulting in sequential single
electron tunneling and masing. We develop a dynamic tuning protocol that allows
us to controllably increase the time-averaged repumping rate of the DQD at a
fixed level detuning, and quantitatively study the transition through the
masing threshold. We further examine the crossover from incoherent to coherent
emission by measuring the photon statistics across the masing transition. The
observed threshold behavior is in agreement with an existing single atom maser
theory when small corrections from lead emission are taken into account
Landau-Zener-Stuckelberg Interferometry of a Single Electron Charge Qubit
We perform Landau-Zener-Stuckelberg interferometry on a single electron GaAs
charge qubit by repeatedly driving the system through an avoided crossing. We
observe coherent destruction of tunneling, where periodic driving with specific
amplitudes inhibits current flow. We probe the quantum dot occupation using a
charge sensor, observing oscillations in the qubit population resulting from
the microwave driving. At a frequency of 9 GHz we observe excitation processes
driven by the absorption of up to 17 photons. Simulations of the qubit
occupancy are in good agreement with the experimental data.Comment: Related papers at http://pettagroup.princeton.ed
Double Quantum Dot Floquet Gain Medium
Strongly driving a two-level quantum system with light leads to a ladder of
Floquet states separated by the photon energy. Nanoscale quantum devices allow
the interplay of confined electrons, phonons, and photons to be studied under
strong driving conditions. Here we show that a single electron in a
periodically driven DQD functions as a "Floquet gain medium," where population
imbalances in the DQD Floquet quasi-energy levels lead to an intricate pattern
of gain and loss features in the cavity response. We further measure a large
intra-cavity photon number n_c in the absence of a cavity drive field, due to
equilibration in the Floquet picture. Our device operates in the absence of a
dc current -- one and the same electron is repeatedly driven to the excited
state to generate population inversion. These results pave the way to future
studies of non-classical light and thermalization of driven quantum systems
Part I - The Distribution and Depuration of Kepone in American Eels, Anguilla Rostrate, from the James River, Virginia. Part II - An Economic Analysis of the Commerical Depuration of Kepone contaminated American Eels, Anguilla rostrata, from the James River, Virginia
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