Measurement of T1 of the ultrashort T2* components in white matter of the brain at 3T.

Recent research demonstrates that white matter of the brain contains not only long T2 components, but a minority of ultrashort T2* components. Adiabatic inversion recovery prepared dual echo ultrashort echo time (IR-dUTE) sequences can be used to selectively image the ultrashort T2* components in white matter of the brain using a clinical whole body scanner. The T2*s of the ultrashort T2* components can be quantified using mono-exponential decay fitting of the IR-dUTE signal at a series of different TEs. However, accurate T1 measurement of the ultrashort T2* components is technically challenging. Efficient suppression of the signal from the majority of long T2 components is essential for robust T1 measurement. In this paper we describe a novel approach to this problem based on the use of IR-dUTE data acquisitions with different TR and TI combinations to selectively detect the signal recovery of the ultrashort T2* components. Exponential recovery curve fitting provides efficient T1 estimation, with minimized contamination from the majority of long T2 components. A rubber phantom and a piece of bovine cortical bone were used for validation of this approach. Six healthy volunteers were studied. An averaged T2* of 0.32 ± 0.09 ms, and a short mean T1 of 226 ± 46 ms were demonstrated for the healthy volunteers at 3T

Programmable quantum state discriminator by Nuclear Magnetic Resonance

In this paper a programmable quantum state discriminator is implemented by using nuclear magnetic resonance. We use a two qubit spin-1/2 system, one for the data qubit and one for the ancilla (programme) qubit. This device does the unambiguous (error free) discrimination of pair of states of the data qubit that are symmetrically located about a fixed state. The device is used to discriminate both, linearly polarized states and elliptically polarized states. The maximum probability of the successful discrimination is achieved by suitably preparing the ancilla qubit. It is also shown that, the probability of discrimination depends on angle of unitary operator of the protocol and ellipticity of the data qubit state.Comment: 22 pages and 9 figure

Nuclear Spins in a Nanoscale Device for Quantum Information Processing

Coherent oscillations between any two levels from four nuclear spin states of I=3/2 have been demonstrated in a nanometre-scale NMR semiconductor device, where nuclear spins are all-electrically controlled. Using this device, we discuss quantum logic operations on two fictitious qubits of the I=3/2 system, and propose a quantum state tomography scheme based on the measurement of longitudinal magnetization, $M_z$.Comment: 5 pages, 4 figure

Quantum information processing by NMR using a 5-qubit system formed by dipolar coupled spins in an oriented molecule

Quantum Information processing by NMR with small number of qubits is well established. Scaling to higher number of qubits is hindered by two major requirements (i) mutual coupling among qubits and (ii) qubit addressability. It has been demonstrated that mutual coupling can be increased by using residual dipolar couplings among spins by orienting the spin system in a liquid crystalline matrix. In such a case, the heteronuclear spins are weakly coupled but the homonuclear spins become strongly coupled. In such circumstances, the strongly coupled spins can no longer be treated as qubits. However, it has been demonstrated elsewhere, that the $2^N$ energy levels of a strongly coupled N spin-1/2 system can be treated as an N-qubit system. For this purpose the various transitions have to be identified to well defined energy levels. This paper consists of two parts. In the first part, the energy level diagram of a heteronuclear 5-spin system is obtained by using a newly developed heteronuclear z-cosy (HET-Z-COSY) experiment. In the second part, implementation of logic gates, preparation of pseudopure states, creation of entanglement and entanglement transfer is demonstrated, validating the use of such systems for quantum information processing.Comment: 23 pages, 8 figure

Approximate Quantum Cloning with Nuclear Magnetic Resonance

Here we describe a Nuclear Magnetic Resonance (NMR) experiment that uses a three qubit NMR device to implement the one to two approximate quantum cloning network of Buzek et al.Comment: 4 pages RevTeX4 including 5 postscript figures. Submitted to PR

A robust broadband fat suppressing phaser T2 preparation module for cardiac magnetic resonance imaging at 3T

Purpose: Designing a new T2 preparation (T2-Prep) module in order to simultaneously provide robust fat suppression and efficient T2 preparation without requiring an additional fat suppression module for T2-weighted imaging at 3T. Methods: The tip-down RF pulse of an adiabatic T2 preparation (T2-Prep) module was replaced by a custom-designed RF excitation pulse that induces a phase difference between water and fat, resulting in a simultaneous T2 preparation of water signals and the suppression of fat signals at the end of the module (now called a phaser adiabatic T2-Prep). Using numerical simulations, in vitro and in vivo ECG-triggered navigator gated acquisitions of the human heart, the blood, myocardium and fat signal-to-noise ratio and right coronary artery (RCA) vessel sharpness using this approach were compared against previously published conventional adiabatic T2-Prep approaches Results: Numerical simulations predicted an increased fat suppression bandwidth and decreased sensitivity against transmit magnetic field inhomogeneities using the proposed approach, while preserving the water T2 preparation capabilities. This was confirmed by the tissue signals acquired on the phantom and the in vivo MRA, which show similar blood and myocardium SNR and CNR and significantly reduced fat SNR compared to the other methods tested. As a result, the RCA conspicuity was significantly increased and the motion artifacts were visually decreased. Conclusion: A novel fat-suppressing T2-preparation method was developed and implemented that demonstrated robust fat suppression and increased vessel sharpness compared with conventional techniques, while preserving its T2 preparation capabilities.Comment: 23 pages, 5 figures, submitted to Magnetic Resonance in Medicin