The quantum nature of bulk ensemble NMR quantum computing — the center of recent heated debate, is addressed. Concepts of the mixed state and entanglement are examined, and the data in a two-qubit liquid NMR quantum ...The quantum nature of bulk ensemble NMR quantum computing — the center of recent heated debate, is addressed. Concepts of the mixed state and entanglement are examined, and the data in a two-qubit liquid NMR quantum computation are analyzed. The main points in this paper are: i) Density matrix describes the 'state' of an average particle in an ensemble. It does not describe the state of an individual particle in an ensemble; ii) Entanglement is a property of the wave function of a microscopic particle (such as a molecule in a liquid NMR sample), and separability of the density matrix cannot be used to measure the entanglement of mixed ensemble; iii) The state evolution in bulk-ensemble NMR quantum computation is quantum-mechanical; iv) The coefficient before the effective pure state density matrix, ?, is a measure of the simultaneity of the molecules in an ensemble. It reflects the intensity of the NMR signal and has no significance in quantifying the entanglement in the bulk ensemble NMR system. The decomposition of the density matrix into product states is only an indication that the ensemble can be prepared by an ensemble with the particles unentangled. We conclude that effective-pure-state NMR quantum computation is genuine, not just classical simulations.展开更多
Since long-lived light bottom squark (sbottom) and its anti-particle with a mass close to the bottomquark have not been excluded by experiments so far, so we would like to consider such a sbottom to combine with itsan...Since long-lived light bottom squark (sbottom) and its anti-particle with a mass close to the bottomquark have not been excluded by experiments so far, so we would like to consider such a sbottom to combine with itsanti-particle to form a color singlet meson-like bound state or to combine with a common anti-quark to form a fermion-like one, or accordingly their anti-particles to form an anti-particle bound system. Namely we calculate the low-lyingspectrum of the systems specifically based on QCD inspired potential model. To be relativistic as much as possible, westart with the framework of Bethe-Salpeter (BS) equation even for non-relativistic binding systems. Finally, we obtainthe requested spectrum by constructing general forms of the BS wave functions and solving the BS equations underinstantaneous approximation.展开更多
文摘The quantum nature of bulk ensemble NMR quantum computing — the center of recent heated debate, is addressed. Concepts of the mixed state and entanglement are examined, and the data in a two-qubit liquid NMR quantum computation are analyzed. The main points in this paper are: i) Density matrix describes the 'state' of an average particle in an ensemble. It does not describe the state of an individual particle in an ensemble; ii) Entanglement is a property of the wave function of a microscopic particle (such as a molecule in a liquid NMR sample), and separability of the density matrix cannot be used to measure the entanglement of mixed ensemble; iii) The state evolution in bulk-ensemble NMR quantum computation is quantum-mechanical; iv) The coefficient before the effective pure state density matrix, ?, is a measure of the simultaneity of the molecules in an ensemble. It reflects the intensity of the NMR signal and has no significance in quantifying the entanglement in the bulk ensemble NMR system. The decomposition of the density matrix into product states is only an indication that the ensemble can be prepared by an ensemble with the particles unentangled. We conclude that effective-pure-state NMR quantum computation is genuine, not just classical simulations.
文摘Since long-lived light bottom squark (sbottom) and its anti-particle with a mass close to the bottomquark have not been excluded by experiments so far, so we would like to consider such a sbottom to combine with itsanti-particle to form a color singlet meson-like bound state or to combine with a common anti-quark to form a fermion-like one, or accordingly their anti-particles to form an anti-particle bound system. Namely we calculate the low-lyingspectrum of the systems specifically based on QCD inspired potential model. To be relativistic as much as possible, westart with the framework of Bethe-Salpeter (BS) equation even for non-relativistic binding systems. Finally, we obtainthe requested spectrum by constructing general forms of the BS wave functions and solving the BS equations underinstantaneous approximation.
