Rongdian Han

Experimental realization of quantum games on a quantum computer.

We generalize the quantum prisoners dilemma to the case where the players share a nonmaximally entangled states. We show that the game exhibits an intriguing structure as a function of the amount of entanglement with two thresholds which separate a classical region, an intermediate region, and a fully quantum region. Furthermore this quantum game is experimentally realized on our nuclear magnetic resonance quantum computer.

Experimental implementation of the quantum random-walk algorithm

The quantum random walk is a possible approach to construct quantum algorithms. Several groups have investigated the quantum random walk and experimental schemes were proposed. In this paper, we present the experimental implementation of the quantum random-walk algorithm on a nuclear-magnetic-resonance quantum computer. We observe that the quantum walk is in sharp contrast to its classical counterpart. In particular, the properties of the quantum walk strongly depends on the quantum entanglement.

Entanglement enhanced multiplayer quantum games

We investigate the 3-player quantum Prisoners Dilemma with a certain strategic space, a particular Nash equilibrium that can remove the original dilemma is found. Based on this equilibrium, we show that the game is enhanced by the entanglement of its initial state.

Implementation of a quantum algorithm to solve the Bernstein-Vazirani parity problem without entanglement on an ensemble quantum computer

Bernstein and Varizani have given the first quantum algorithm to solve parity problem in which a strong violation of the classical imformation theoritic bound comes about. In this paper, we refine this algorithm with fewer resource and implement a two qubits algorithm in a single query on an ensemble quantum computer for the first time.

PLAYING PRISONER'S DILEMMA WITH QUANTUM RULES

Quantum game theory is a recently developing field of physical research. In this paper, we investigate quantum games in a systematic way. With the famous instance of the Prisoners Dilemma, we present the fascinating properties of quantum games in different conditions, i.e. different number of the players, different strategic space of the players and different amount of the entanglement involved.

Implementing universal multiqubit quantum logic gates in three- and four-spin systems at room temperature

In this paper, we present the experimental realization of multiqubit gates

Vacancy defects in epitaxial La0.7Sr0.3MnO3thin films probed by a slow positron beam

{\ensuremath{\Lambda}}_{n}(

Proton emission in reaction of 14.6-MeV neutrons with natural iron

NOT) in macroscopic ensemble of three-qubit and four-qubit molecules. Instead of depending heavily on the two-bit universal gate, which served as the basic quantum operation in quantum computing, we use pulses of well-defined frequency and length that simultaneously apply to all qubits in a quantum register. It appears that this method is experimentally convenient when this procedure is extended to more qubits on some quantum computation, and it can also be used in other physical systems.

The 93Nb(n,xp) Reaction at En = 14.6 MeV

Vacancy defects in epitaxial La0.7Sr0.3MnO3 (LSMO) thin films on LaAlO3 substrates were detected using a variable energy positron beam. The line-shape S parameter of the epitaxial thin films deposited at different oxygen pressures was measured as a function of the implanting positron energy E. Our results show that the S parameter of the films changes non-monotonically with their deposition oxygen pressures. For the films deposited at lower oxygen pressures, the increase in S value in the films is attributed to the increase in oxygen vacancies and/or related defect–VO complexes, and for those deposited at higher oxygen pressures, the larger S parameter of the films is caused by the grain boundaries and/or metallic ion vacancies. The surface morphology of the films was also characterized to analyse the open volume defects in the LSMO films.

Implementation of Quantum Logic Gates by Nuclear Magnetic Resonance Spectroscopy

The energy spectra and angular distributions of proton emission in a reaction of {sup nat}Fe(n,xp) at a neutron energy of 14.6 MeV are measured by the University of Science and Technology of China multitelescope system. The double-differential cross sections of 16 reaction angles from 25 to 164.5 deg are obtained in this measurement. The statistical errors are reduced largely because of the thick target used. The angular distributions show a slightly energy-dependent forward-backward asymmetry. The angle-integrated proton spectrum is compared with theoretical calculations and other results. The total proton-emission cross section is in fair agreement with the prediction and evaluation.