Tsing Hua Univ, Dept Phys, Beijing 100084, Peoples R China; Lab Quantum Computat & Quantum Measurement, Beijing 100084, Peoples R China; Tsing Hua Univ, Ctr Atom & Mol Nanosci, Beijing 100084, Peoples R China; Chinese Acad Sci, Inst Theoret Phys, Beijing 100080, Peoples R China; Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA; Tsing Hua Univ, Dept Chem, Beijing 100084, Peoples R China
英文摘要:
The quantum nature of bulk ensemble NAIR quantum computing - the center of recent heated debate, is addressed. Concepts of the mixed state and entanglement arc examined, and the data in a two-qubit liquid NAIR 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 NAIR sample), and separability of the density matrix cannot be used to measure the entanglement of mixed ensemble; iii) The state evolution in bulk-ensemble NAIR quantum computation is quantum-mechanical; iv) The coefficient before the effective pure state density matrix, c, is a measure of the simultaneity of the molecules in an ensemble. It reflects the intensity of the NAIR signal and has no significance in quantifying the entanglement in the bulk ensemble NAIR 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 NAIR quantum computation is genuine, not just classical simulations.
