827 research outputs found
The Quantum Socket: Three-Dimensional Wiring for Extensible Quantum Computing
Quantum computing architectures are on the verge of scalability, a key
requirement for the implementation of a universal quantum computer. The next
stage in this quest is the realization of quantum error correction codes, which
will mitigate the impact of faulty quantum information on a quantum computer.
Architectures with ten or more quantum bits (qubits) have been realized using
trapped ions and superconducting circuits. While these implementations are
potentially scalable, true scalability will require systems engineering to
combine quantum and classical hardware. One technology demanding imminent
efforts is the realization of a suitable wiring method for the control and
measurement of a large number of qubits. In this work, we introduce an
interconnect solution for solid-state qubits: The quantum socket. The quantum
socket fully exploits the third dimension to connect classical electronics to
qubits with higher density and better performance than two-dimensional methods
based on wire bonding. The quantum socket is based on spring-mounted micro
wires the three-dimensional wires that push directly on a micro-fabricated
chip, making electrical contact. A small wire cross section (~1 mmm), nearly
non-magnetic components, and functionality at low temperatures make the quantum
socket ideal to operate solid-state qubits. The wires have a coaxial geometry
and operate over a frequency range from DC to 8 GHz, with a contact resistance
of ~150 mohm, an impedance mismatch of ~10 ohm, and minimal crosstalk. As a
proof of principle, we fabricated and used a quantum socket to measure
superconducting resonators at a temperature of ~10 mK.Comment: Main: 31 pages, 19 figs., 8 tables, 8 apps.; suppl.: 4 pages, 5 figs.
(HiRes figs. and movies on request). Submitte
Engineering the Level Structure of a Giant Artificial Atom in Waveguide Quantum Electrodynamics
Engineering light-matter interactions at the quantum level has been central
to the pursuit of quantum optics for decades. Traditionally, this has been done
by coupling emitters, typically natural atoms and ions, to quantized
electromagnetic fields in optical and microwave cavities. In these systems, the
emitter is approximated as an idealized dipole, as its physical size is orders
of magnitude smaller than the wavelength of light. Recently, artificial atoms
made from superconducting circuits have enabled new frontiers in light-matter
coupling, including the study of "giant" atoms which cannot be approximated as
simple dipoles. Here, we explore a new implementation of a giant artificial
atom, formed from a transmon qubit coupled to propagating microwaves at
multiple points along an open transmission line. The nature of this coupling
allows the qubit radiation field to interfere with itself leading to some
striking giant-atom effects. For instance, we observe strong
frequency-dependent couplings of the qubit energy levels to the electromagnetic
modes of the transmission line. Combined with the ability to in situ tune the
qubit energy levels, we show that we can modify the relative coupling rates of
multiple qubit transitions by more than an order of magnitude. By doing so, we
engineer a metastable excited state, allowing us to operate the giant transmon
as an effective lambda system where we clearly demonstrate electromagnetically
induced transparency.Comment: 12 pages, 8 figure
A comparison of methods to quantify greenhouse gas emissions of cropping systems in LCA
Carbon dioxide and nitrous oxide are two important greenhouse gases (GHG) released from cropping systems. Their emissions can vary substantially with climate, soil, and crop management. While different methods are available to account for GHG emissions in life cycle assessments (LCA) of crop production, there are no standard procedures. In this study, the objectives were: (i) to compare several methods of estimating CO2 and N2O emissions for a LCA of cropping systems and (ii) to estimate the relative contribution of soil GHG emissions to the overall global warming potential (GWP) using results from a field experiment located in Manitoba, Canada. The methods were: (A) measurements; (B) Tier I and (C) Tier II IPCC (Intergovernmental panel on Climate Change) methodology, (D) a simple carbon model combined with Intergovernmental Panel for Climate Change (IPCC) Tier II methodology for soil N2O emissions, and (E) the DNDC (DeNitrification DeComposition) agroecosystem model. The estimated GWPs (−7.2–17 Mg CO2eq ha−1 y−1; −80 to 600 kg CO2eq GJ−1 y−1) were similar to previous results in North America and no statistical difference was found between GWP based on methods D and E and GWP based on observations. The five methods gave estimates of soil CO2 emissions that were not statistically different from each other, whereas for N2O emissions only DNDC estimates were similar to observations. Across crop types, all methods gave comparable CO2 and N2O emission estimates for perennial and legume crops, but only DNDC gave similar results with respect to observations for both annual and cereal crops. Whilst the results should be confirmed for other locations, the agroecosystem model and method D can be used, at certainly one selected site, in place of observations for estimating GHGs in agricultural LCA
Recommended from our members
Employing an orthotopic model to study the role of epithelial-mesenchymal transition in bladder cancer metastasis.
Epithelial-to-mesenchymal transition (EMT) has been implicated in the progression of bladder cancer. To study its contribution to bladder cancer metastasis, we established new xenograft models derived from human bladder cancer cell lines utilizing an orthotopic "recycling" technique that allowed us to isolate and examine the primary tumor and its corresponding circulating tumor cells (CTC's) and metastatic lesions. Using whole genome mRNA expression profiling, we found that a reversible epithelial-to-mesenchymal transition (EMT) characterized by TGFβ pathway activation and SNAIL expression was associated with the accumulation of CTCs. Finally, we observed that conditional silencing of SNAIL completely blocked CTC production and regional/distant metastasis. Using this unique bladder cancer xenograft model, we conclude that metastasis is dependent on a reversible EMT mediated by SNAIL
A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam
A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors
located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This
new SBN Program will deliver a rich and compelling physics opportunity,
including the ability to resolve a class of experimental anomalies in neutrino
physics and to perform the most sensitive search to date for sterile neutrinos
at the eV mass-scale through both appearance and disappearance oscillation
channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND
and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we
estimate that a search for muon neutrino to electron neutrino appearance can be
performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter
region. In this proposal for the SBN Program, we describe the physics analysis,
the conceptual design of the LAr1-ND detector, the design and refurbishment of
the T600 detector, the necessary infrastructure required to execute the
program, and a possible reconfiguration of the BNB target and horn system to
improve its performance for oscillation searches.Comment: 209 pages, 129 figure
Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF
The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at
the Fermilab Long-Baseline Neutrino Facility (LBNF) is described
- …