复旦量子力学讲义——qm2_chapter7课件.ppt

Chapter 7Quantum Entanglement and Quantum Information §7.1 Pure states and mixed states Introduction: Quantum entanglement describes the coherence of two or many quantum states according to the superposition principle of quantum states. Energy: interactions, conservation laws, work… Entropy: information, order and disorder… Entanglement: coherence, teleportation… §7.1 Pure states and mixed states Pure state §7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.1 Pure states and mixed states § 7.2 Entangled states and Bell basis § 7.2 Entangled states and Bell basis § 7.2 Entangled states and Bell basis § 7.2 Entangled states and Bell basis § 7.2 Entangled states and Bell basis § 7.2 Entangled states and Bell basis § 7.2 Entangled states and Bell basis § 7.2 Entangled states and Bell basis § 7.3 Schordinger cat and which way experiments § 7.3 Schordinger cat and which way experiments § 7.3 Schordinger cat and which way experiments § 7.3 Schordinger cat and which way experiments § 7.4 Measurement and decoherence § 7.4 Measurement and decoherence § 7.5 Quantum teleporation § 7.5 Quantum teleporation § 7.5 Quantum teleporation § 7.5 Quantum teleporation § 7.5 Quantum teleporation The particle 2, 3 with its spin ? are at the entangled state EPR pair: In the Bell basis * * System A: Systems A+B: Pure state Density matrix: In the base of the representation O The average value of a quantity F: Mixed state: the non-coherent mixture of two or many pure states System A: In the base of the representation O Systems A+B: the reduced density matrix If is a observable quantity of system A, its average value: is a unit operator of system B. is called the reduced density matrix. The prope