448 research outputs found
A n-qubit controlled phase gate with superconducting quantum interference devices coupled to a resonator
We present a way to realize a -qubit controlled phase gate with
superconducting quantum interference devices (SQUIDs) by coupling them to a
superconducting resonator. In this proposal, the two logical states of a qubit
are represented by the two lowest levels of a SQUID. An intermediate level of
each SQUID is utilized to facilitate coherent control and manipulation of
quantum states of the qubits. It is interesting to note that a -qubit
controlled phase gate can be achieved with SQUIDs by successively applying
a Jaynes-Cummings pulse to each of the control SQUIDs before and
after a Jaynes-Cummings pulse on the target SQUID.Comment: 9 pages, 4 figures, 1 table, RevTeX, Resubmitted to Phys. Rev.
A unified approach to realize universal quantum gates in a coupled two-qubit system with fixed always-on coupling
We demonstrate that in a coupled two-qubit system any single-qubit gate can
be decomposed into two conditional two-qubit gates and that any conditional
two-qubit gate can be implemented by a manipulation analogous to that used for
a controlled two-qubit gate. Based on this we present a unified approach to
implement universal single-qubit and two-qubit gates in a coupled two-qubit
system with fixed always-on coupling. This approach requires neither
supplementary circuit or additional physical qubits to control the coupling nor
extra hardware to adjust the energy level structure. The feasibility of this
approach is demonstrated by numerical simulation of single-qubit gates and
creation of two-qubit Bell states in rf-driven inductively coupled two SQUID
flux qubits with realistic device parameters and constant always-on coupling.Comment: 4 pages, 3 figure
Generation of GHZ entangled states of photons in multiple cavities via a superconducting qutrit or an atom through resonant interaction
We propose an efficient method to generate a GHZ entangled state of n photons
in n microwave cavities (or resonators) via resonant interaction to a single
superconducting qutrit. The deployment of a qutrit, instead of a qubit, as the
coupler enables us to use resonant interactions exclusively for all
qutrit-cavity and qutrit-pulse operations. This unique approach significantly
shortens the time of operation which is advantageous to reducing the adverse
effects of qutrit decoherence and cavity decay on fidelity of the protocol.
Furthermore, the protocol involves no measurement on either the state of qutrit
or cavity photons. We also show that the protocol can be generalized to other
systems by replacing the superconducting qutrit coupler with different types of
physical qutrit, such as an atom in the case of cavity QED, to accomplish the
same task.Comment: 11 pages, 5 figures, accepted by Phys. Rev.
Quantum logical gates with four-level SQUIDs coupled to a superconducting resonator
We propose a way for realizing a two-qubit controlled phase gate with
superconducting quantum interference devices (SQUIDs) coupled to a
superconducting resonator. In this proposal, the two lowest levels of each
SQUID serve as the logical states and two intermediate levels of each SQUID are
used for the gate realization. We show that neither adjustment of SQUID level
spacings during the gate operation nor uniformity in SQUID parameters is
required by this proposal. In addition, this proposal does not require the
adiabatic passage or a second-order detuning and thus the gate is much faster.Comment: 6 pages, 3 figure
Generating entanglement between microwave photons and qubits in multiple cavities coupled by a superconducting qutrit
We discuss how to generate entangled coherent states of four
\textrm{microwave} resonators \textrm{(a.k.a. cavities)} coupled by a
superconducting qubit. We also show \textrm{that} a GHZ state of four
superconducting qubits embedded in four different resonators \textrm{can be
created with this scheme}. In principle, \textrm{the proposed method} can be
extended to create an entangled coherent state of resonators and to prepare
a Greenberger-Horne-Zeilinger (GHZ) state of qubits distributed over
cavities in a quantum network. In addition, it is noted that four resonators
coupled by a coupler qubit may be used as a basic circuit block to build a
two-dimensional quantum network, which is useful for scalable quantum
information processing.Comment: 13 pages, 7 figure
Development of Protective Gloves for Gardening
A house with a beautiful yard will not only increase the property value but also help the owner fit into a local community (Robbins, Polderman, & Birkenholtz, 2001), build connections with neighbors, and demonstrate personal values (Nassauer, 1988). Moreover, gardening could benefit people of different ages. Gardening practice teaches children patience, establishes a moral code, enhances a sense of responsibility, develops the love of nature and improves social cohesion (Montessori, 1964)
Angiotensin II Type 1 Receptor Autoantibodies in Primary Aldosteronism
Primary aldosteronism (PA) is the most common form of endocrine hypertension. Agonistic autoantibodies against the angiotensin II type 1 receptor (AT(1)R-Abs) have been described in transplantation medicine and women with pre-eclampsia and more recently in patients with PA. Any functional role of AT(1)R-Abs in either of the two main subtypes of PA (aldosterone-producing adenoma or bilateral adrenal hyperplasia) requires clarification. In this review, we discuss the studies performed to date on AT(1)R-Abs in PA
Single-photon-driven high-order sideband transitions in an ultrastrongly coupled circuit quantum electrodynamics system
We report the experimental observation of high-order sideband transitions at
the single-photon level in a quantum circuit system of a flux qubit
ultrastrongly coupled to a coplanar waveguide resonator. With the coupling
strength reaching 10% of the resonator's fundamental frequency, we obtain clear
signatures of higher-order red and first-order blue-sideband transitions, which
are mainly due to the ultrastrong Rabi coupling. Our observation advances the
understanding of ultrastrongly-coupled systems and paves the way to study
high-order processes in the quantum Rabi model at the single-photon level.Comment: Accepted in Physical Review A. 12 pages, 6 figure
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