Quantum logical operations for spin 3/2 quadrupolar nuclei monitored by quantum state tomography

Bonk, Fábio Aurélio; deAzevedo, Eduardo R.; Sarthour, R. S.; Bulnes, J. D.; Freitas, Jair C. C.; Guimarães, A.P.; Bonagamba, Tito J.

doi:10.1016/j.jmr.2005.04.009

Cited by 26 publications

(45 citation statements)

References 23 publications

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“…(18a)-(18j), where we do not have distinct spectral densities for each qubit. We recall that we can consider this I = 3/2 system as an effective two-qubit one since we can manipulate the transitions between the energy levels of these logical qubits (i.e., the nuclear transitions of the quadrupolar spin) just as it is performed in the case of physical qubits [43].…”

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confidence: 99%

Nonclassical correlation in NMR quadrupolar systems

et al. 2010

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The existence of quantum correlation (as revealed by quantum discord), other than entanglement and its role in quantum-information processing (QIP), is a current subject for discussion. In particular, it has been suggested that this nonclassical correlation may provide computational speedup for some quantum algorithms. In this regard, bulk nuclear magnetic resonance (NMR) has been successfully used as a test bench for many QIP implementations, although it has also been continuously criticized for not presenting entanglement in most of the systems used so far. In this paper, we report a theoretical and experimental study on the dynamics of quantum and classical correlations in an NMR quadrupolar system. We present a method for computing the correlations from experimental NMR deviation-density matrices and show that, given the action of the nuclear-spin environment, the relaxation produces a monotonic time decay in the correlations. Although the experimental realizations were performed in a specific quadrupolar system, the main results presented here can be applied to whichever system uses a deviation-density matrix formalism.

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Section: Fig 2 (Color Online)mentioning

confidence: 99%

Nonclassical correlation in NMR quadrupolar systems

et al. 2010

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“…Together with proper temporal or spatial averaging procedures and evolution under spin interactions [23], the RF pulse can be specially designed to prepare any two-qubit computational base states, as well as their superpositions, starting from the thermal equilibrium state [2,[24][25][26].…”

Section: Measuring Quantum and Classical Correlations In Nuclear Magnmentioning

confidence: 99%

On the quantumness of correlations in nuclear magnetic resonance

Soares-Pinto

Auccaise

Maziero

et al. 2012

Phil. Trans. R. Soc. A.

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Nuclear magnetic resonance (NMR) was successfully employed to test several protocols and ideas in quantum information science. In most of these implementations, the existence of entanglement was ruled out. This fact introduced concerns and questions about the quantum nature of such bench tests. In this paper, we address some issues related to the non-classical aspects of NMR systems. We discuss some experiments where the quantum aspects of this system are supported by quantum correlations of separable states. Such quantumness, beyond the entanglement-separability paradigm, is revealed via a departure between the quantum and the classical versions of information theory. In this scenario, the concept of quantum discord seems to play an important role. We also present an experimental implementation of an analogue of the single-photon MachZehnder interferometer employing two nuclear spins to encode the interferometric paths. This experiment illustrates how non-classical correlations of separable states may be used to simulate quantum dynamics. The results obtained are completely equivalent to the optical scenario, where entanglement (between two field modes) may be present.

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“…From the application of a sequence of such pulses, by setting the pulses duration, phase and amplitude, a very fine control over the density matrix population and coherences can be achieved, and it is possible to generate all two-qubit computational base states, also superposition and entangled states [22,29]. It is important to note that these entangled states are called pseudo-entangled states because ǫ ∼ 10 −5 , which makes ρ pps always separable even when ρ 1 is an entagled state [32].…”

Section: Nmr Two Qubit Systemsmentioning

confidence: 99%

Writing Electronic Ferromagnetic States in a High-Temperature Paramagnetic Nuclear Spin System

Soares-Pinto

Teles

Souza

et al. 2011

Int. J. Quantum Inform.

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In this paper we use the Nuclear Magnetic Resonance (NMR) to write eletronic states of a ferromagnetic system into a high-temperature paramagnetic nuclear spins. Through the control of phase and duration of radiofrequency pulses we set the NMR density matrix populations, and apply the technique of quantum state tomography to experimentally obtain the matrix elements of the system, from which we calculate the temperature dependence of magnetization for different magnetic fields. The effects of the variation of temperature and magnetic field over the populations can be mapped in the angles of spins rotations, carried out by the RF pulses. The experimental results are compared to the Brillouin functions of ferromagnetic ordered systems in the mean field approximation for two cases: the mean field is given by (i) B = B0 + λM and (ii) B = B0 + λM + λ ′ M 3 , where B0 is the external magnetic field, and λ, λ ′ are mean field parameters. The first case exhibits second order transition, whereas the second case has first order transition with temperature hysteresis. The NMR simulations are in good agreement with the magnetic predictions.

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Quantum logical operations for spin 3/2 quadrupolar nuclei monitored by quantum state tomography

Cited by 26 publications

References 23 publications

Nonclassical correlation in NMR quadrupolar systems

Nonclassical correlation in NMR quadrupolar systems

On the quantumness of correlations in nuclear magnetic resonance

Writing Electronic Ferromagnetic States in a High-Temperature Paramagnetic Nuclear Spin System

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