1,741 research outputs found
Thin film dielectric microstrip kinetic inductance detectors
Microwave Kinetic Inductance Detectors, or MKIDs, are a type of low
temperature detector that exhibit intrinsic frequency domain multiplexing at
microwave frequencies. We present the first theory and measurements on a MKID
based on a microstrip transmission line resonator. A complete characterization
of the dielectric loss and noise properties of these resonators is performed,
and agrees well with the derived theory. A competitive noise equivalent power
of 5 W Hz at 1 Hz has been demonstrated. The
resonators exhibit the highest quality factors known in a microstrip resonator
with a deposited thin film dielectric.Comment: 10 pages, 4 figures, APL accepte
Computing prime factors with a Josephson phase qubit quantum processor
A quantum processor (QuP) can be used to exploit quantum mechanics to find
the prime factors of composite numbers[1]. Compiled versions of Shor's
algorithm have been demonstrated on ensemble quantum systems[2] and photonic
systems[3-5], however this has yet to be shown using solid state quantum bits
(qubits). Two advantages of superconducting qubit architectures are the use of
conventional microfabrication techniques, which allow straightforward scaling
to large numbers of qubits, and a toolkit of circuit elements that can be used
to engineer a variety of qubit types and interactions[6, 7]. Using a number of
recent qubit control and hardware advances [7-13], here we demonstrate a
nine-quantum-element solid-state QuP and show three experiments to highlight
its capabilities. We begin by characterizing the device with spectroscopy.
Next, we produces coherent interactions between five qubits and verify bi- and
tripartite entanglement via quantum state tomography (QST) [8, 12, 14, 15]. In
the final experiment, we run a three-qubit compiled version of Shor's algorithm
to factor the number 15, and successfully find the prime factors 48% of the
time. Improvements in the superconducting qubit coherence times and more
complex circuits should provide the resources necessary to factor larger
composite numbers and run more intricate quantum algorithms.Comment: 5 pages, 3 figure
PickCells: A Physically Reconfigurable Cell-composed Touchscreen
Touchscreens are the predominant medium for interactions with digital services; however, their current fixed form factor narrows the scope for rich physical interactions by limiting interaction possibilities to a single, planar surface. In this paper we introduce the concept of PickCells, a fully reconfigurable device concept composed of cells, that breaks the mould of rigid screens and explores a modular system that affords rich sets of tangible interactions and novel acrossdevice relationships. Through a series of co-design activities – involving HCI experts and potential end-users of such systems – we synthesised a design space aimed at inspiring future research, giving researchers and designers a framework in which to explore modular screen interactions. The design space we propose unifies existing works on modular touch surfaces under a general framework and broadens horizons by opening up unexplored spaces providing new interaction possibilities. In this paper, we present the PickCells concept, a design space of modular touch surfaces, and propose a toolkit for quick scenario prototyping
Planar Superconducting Resonators with Internal Quality Factors above One Million
We describe the fabrication and measurement of microwave coplanar waveguide
resonators with internal quality factors above 10 million at high microwave
powers and over 1 million at low powers, with the best low power results
approaching 2 million, corresponding to ~1 photon in the resonator. These
quality factors are achieved by controllably producing very smooth and clean
interfaces between the resonators' aluminum metallization and the underlying
single crystal sapphire substrate. Additionally, we describe a method for
analyzing the resonator microwave response, with which we can directly
determine the internal quality factor and frequency of a resonator embedded in
an imperfect measurement circuit.Comment: 4 pages, 3 figures, 1 tabl
Excitation of superconducting qubits from hot non-equilibrium quasiparticles
Superconducting qubits probe environmental defects such as non-equilibrium
quasiparticles, an important source of decoherence. We show that "hot"
non-equilibrium quasiparticles, with energies above the superconducting gap,
affect qubits differently from quasiparticles at the gap, implying qubits can
probe the dynamic quasiparticle energy distribution. For hot quasiparticles, we
predict a non-neligable increase in the qubit excited state probability P_e. By
injecting hot quasiparticles into a qubit, we experimentally measure an
increase of P_e in semi-quantitative agreement with the model and rule out the
typically assumed thermal distribution.Comment: Main paper: 5 pages, 5 figures. Supplement: 1 page, 1 figure, 1
table. Updated to user-prepared accepted version. Key changes: Supplement
added, Introduction rewritten, Figs.2,3,5 revised, Fig.4 adde
Multiplexed dispersive readout of superconducting phase qubits
We introduce a frequency-multiplexed readout scheme for superconducting phase
qubits. Using a quantum circuit with four phase qubits, we couple each qubit to
a separate lumped-element superconducting readout resonator, with the readout
resonators connected in parallel to a single measurement line. The readout
resonators and control electronics are designed so that all four qubits can be
read out simultaneously using frequency multiplexing on the one measurement
line. This technology provides a highly efficient and compact means for reading
out multiple qubits, a significant advantage for scaling up to larger numbers
of qubits.Comment: 4 pages, 4 figure
Energy decay and frequency shift of a superconducting qubit from non-equilibrium quasiparticles
Quasiparticles are an important decoherence mechanism in superconducting
qubits, and can be described with a complex admittance that is a generalization
of the Mattis-Bardeen theory. By injecting non-equilibrium quasiparticles with
a tunnel junction, we verify qualitatively the expected change of the decay
rate and frequency in a phase qubit. With their relative change in agreement to
within 4% of prediction, the theory can be reliably used to infer quasiparticle
density. We describe how settling of the decay rate may allow determination of
whether qubit energy relaxation is limited by non-equilibrium quasiparticles.Comment: Main paper: 4 pages, 3 figures, 1 table. Supplementary material: 8
pages, 3 figure
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