1,138 research outputs found
Minimum construction of two-qubit quantum operations
Optimal construction of quantum operations is a fundamental problem in the
realization of quantum computation. We here introduce a newly discovered
quantum gate, B, that can implement any arbitrary two-qubit quantum operation
with minimal number of both two- and single-qubit gates. We show this by giving
an analytic circuit that implements a generic nonlocal two-qubit operation from
just two applications of the B gate. We also demonstrate that for the highly
scalable Josephson junction charge qubits, the B gate is also more easily and
quickly generated than the CNOT gate for physically feasible parameters.Comment: 4 page
Switched Control of Electron Nuclear Spin Systems
In this article, we study control of electron-nuclear spin dynamics at
magnetic field strengths where the Larmor frequency of the nucleus is
comparable to the hyperfine coupling strength. The quantization axis for the
nuclear spin differs from the static B_0 field direction and depends on the
state of the electron spin. The quantization axis can be switched by flipping
the state of electron spin, allowing for universal control on nuclear spin
states. We show that by performing a sequence of flips (each followed by a
suitable delay), we can perform any desired rotation on the nuclear spins,
which can also be conditioned on the state of the electron spin. These
operations, combined with electron spin rotations can be used to synthesize any
unitary transformation on the coupled electron-nuclear spin system. We discuss
how these methods can be used for design of experiments for transfer of
polarization from the electron to the nuclear spins
Preparation of Decoherence Free Cluster States with Optical Superlattices
We present a protocol to prepare decoherence free cluster states using
ultracold atoms loaded in a two dimensional superlattice. The superlattice
geometry leads to an array of 2*2 plaquettes, each of them holding four
spin-1/2 particles that can be used for encoding a single logical qubit in the
two-fold singlet subspace, insensitive to uniform magnetic field fluctuations
in any direction. Dynamical manipulation of the supperlattice yields distinct
inter and intra plaquette interactions and permits to realize one qubit and two
qubit gates with high fidelity, leading to the generation of universal cluster
states for measurement based quantum computation. Our proposal based on inter
and intra plaquette interactions also opens the path to study polymerized
Hamiltonians which support ground states describing arbitrary quantum circuits.Comment: 17 pages, 12 figure
Total Molecular Gas Masses of Planck - Herschel Selected Strongly Lensed Hyper Luminous Infrared Galaxies
We report the detection of CO(1 - 0) line emission from seven Planck and
Herschel selected hyper luminous (LIR(8-1000um) > 10^13Lsun) infrared galaxies
with the Green Bank Telescope (GBT). CO(1 - 0) measurements are a vital tool to
trace the bulk molecular gas mass across all redshifts. Our results place tight
constraints on the total gas content of these most apparently luminous high-z
star-forming galaxies (apparent IR luminosities of LIR > 10^(13-14) Lsun),
while we confirm their predetermined redshifts measured using the Large
Millimeter Telescope, LMT (zCO = 1.33 - 3.26). The CO(1 - 0) lines show similar
profiles as compared to Jup = 2 -4 transitions previously observed with the
LMT. We report enhanced infrared to CO line luminosity ratios of
= 110 (pm 22) Lsun(K km s^-1 pc^-2)^-1 compared to normal
star-forming galaxies, yet similar to those of well-studied IR-luminous
galaxies at high-z. We find average brightness temperature ratios of =
0.93 (2 sources), = 0.34 (5 sources), and = 0.18 (1 source). The
r31 and r41 values are roughly half the average values for SMGs. We estimate
the total gas mass content as uMH2 = (0.9 - 27.2) x 10^11(alphaCO/0.8)Msun,
where u is the magnification factor and alphaCO is the CO line luminosity to
molecular hydrogen gas mass conversion factor. The rapid gas depletion times
are, on average, tau = 80 Myr, which reveal vigorous starburst activity, and
contrast the Gyr depletion timescales observed in local, normal star-forming
galaxies.Comment: published in MNRAS, 9pages, 5fig
Fucoidan and cancer: A multifunctional molecule with anti-tumor potential
There is a wide variety of cancer types yet, all share some common cellular and molecular behaviors. Most of the chemotherapeutic agents used in cancer treatment are designed to target common deregulated mechanisms within cancer cells. Many healthy tissues are also affected by the cytotoxic effects of these chemical agents. Fucoidan, a natural component of brown seaweed, has anti-cancer activity against various cancer types by targeting key apoptotic molecules. It also has beneficial effects as it can protect against toxicity associated with chemotherapeutic agents and radiation. Thus the synergistic effect of fucoidan with current anti-cancer agents is of considerable interest. This review discusses the mechanisms by which fucoidan retards tumor development, eradicates tumor cells and synergizes with anti-cancer chemotherapeutic agents. Challenges to the development of fucoidan as an anti-cancer agent will also be discussed
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