256 research outputs found
The Effect of Uncertainty in Regulatory Delay on the Rate of Innovation
Earlier studies examining house pricing have mainly focused on the secondary market and have often overlooked the primary market and newly produced housing units. This paper studies the pricing strategies in the primary housing market, as that segment differs from the secondary market. By using data from one newly produced housing project, we are able to exclude a number of project-specific factors, as they are nearly identical for all observations. This allows us to focus on factors that are directly observable and require very little assessment or evaluation in our estimations of list prices, selling prices and selling times. The empirical results exhibit a close relationship between list- and selling prices, but a few factors differ significantly between the two. Such differences could indicate a misinterpretation of the market by the seller. The time-on-market model shows that a number of factors affect selling times as well. The results indicate a relationship between "mispriced" factors and their impact on the selling times, where "over-priced" factors seem to prolong the time-on-market and "under-priced" factors seem to shorten the time-on-market. By dividing the units into different price ranges, it becomes clear that high-priced housing is more difficult to price and take longer to sell. This relationship is strengthened by a degree-of-overpricing variable, which exhibits a positive sign in the time-on-market model. The effect is the strongest in low-priced units and not significant for higher-priced units. Other factors that affect pricing strategies require a broader discussion. Analogies from similar consumer good markets indicate that pricing strategies are dependent on the types of customers in the target groups as well as the stage in the project life-cycle
Time-Reversal Symmetry and Universal Conductance Fluctuations in a Driven Two-Level System
In the presence of time-reversal symmetry, quantum interference gives strong
corrections to the electric conductivity of disordered systems. The
self-interference of an electron wavefunction traveling time-reversed paths
leads to effects such as weak localization and universal conductance
fluctuations. Here, we investigate the effects of broken time-reversal symmetry
in a driven artificial two-level system. Using a superconducting flux qubit, we
implement scattering events as multiple Landau-Zener transitions by driving the
qubit periodically back and forth through an avoided crossing. Interference
between different qubit trajectories give rise to a speckle pattern in the
qubit transition rate, similar to the interference patterns created when
coherent light is scattered off a disordered potential. Since the scattering
events are imposed by the driving protocol, we can control the time-reversal
symmetry of the system by making the drive waveform symmetric or asymmetric in
time. We find that the fluctuations of the transition rate exhibit a sharp peak
when the drive is time-symmetric, similar to universal conductance fluctuations
in electronic transport through mesoscopic systems
Noise correlations in a flux qubit with tunable tunnel coupling
We have measured flux-noise correlations in a tunable superconducting flux
qubit. The device consists of two loops that independently control the qubit's
energy splitting and tunnel coupling. Low frequency flux noise in the loops
causes fluctuations of the qubit frequency and leads to dephasing. Since the
noises in the two loops couple to different terms of the qubit Hamiltonian, a
measurement of the dephasing rate at different bias points provides a way to
extract both the amplitude and the sign of the noise correlations. We find that
the flux fluctuations in the two loops are anti-correlated, consistent with a
model where the flux noise is generated by randomly oriented unpaired spins on
the metal surface.Comment: 7 pages, including supplementary materia
Correlated Counting of Single Electrons in a Nanowire Double Quantum Dot
We report on correlated real-time detection of individual electrons in an
InAs nanowire double quantum dot. Two self-aligned quantum point contacts in an
underlying two-dimensional electron gas material serve as highly sensitive
charge detectors for the double quantum dot. Tunnel processes of individual
electrons and all tunnel rates are determined by simultaneous measurements of
the correlated signals of the quantum point contacts.Comment: 11 pages, 4 figures; http://stacks.iop.org/1367-2630/11/01300
S-RASTER: Contraction Clustering for Evolving Data Streams
Contraction Clustering (RASTER) is a single-pass algorithm for density-based
clustering of 2D data. It can process arbitrary amounts of data in linear time
and in constant memory, quickly identifying approximate clusters. It also
exhibits good scalability in the presence of multiple CPU cores. RASTER
exhibits very competitive performance compared to standard clustering
algorithms, but at the cost of decreased precision. Yet, RASTER is limited to
batch processing and unable to identify clusters that only exist temporarily.
In contrast, S-RASTER is an adaptation of RASTER to the stream processing
paradigm that is able to identify clusters in evolving data streams. This
algorithm retains the main benefits of its parent algorithm, i.e. single-pass
linear time cost and constant memory requirements for each discrete time step
within a sliding window. The sliding window is efficiently pruned, and
clustering is still performed in linear time. Like RASTER, S-RASTER trades off
an often negligible amount of precision for speed. Our evaluation shows that
competing algorithms are at least 50% slower. Furthermore, S-RASTER shows good
qualitative results, based on standard metrics. It is very well suited to
real-world scenarios where clustering does not happen continually but only
periodically.Comment: 24 pages, 5 figures, 2 table
A tunable coupling scheme for implementing high-fidelity two-qubit gates
The prospect of computational hardware with quantum advantage relies
critically on the quality of quantum gate operations. Imperfect two-qubit gates
is a major bottleneck for achieving scalable quantum information processors.
Here, we propose a generalizable and extensible scheme for a two-qubit coupler
switch that controls the qubit-qubit coupling by modulating the coupler
frequency. Two-qubit gate operations can be implemented by operating the
coupler in the dispersive regime, which is non-invasive to the qubit states. We
investigate the performance of the scheme by simulating a universal two-qubit
gate on a superconducting quantum circuit, and find that errors from known
parasitic effects are strongly suppressed. The scheme is compatible with
existing high-coherence hardware, thereby promising a higher gate fidelity with
current technologies
- …