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topic:qm:postulates [2022/12/09 19:11] samueltopic:qm:postulates [2023/02/15 18:26] (current) samuel
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 The system is completely described by its state vector, which is a unit vector in the system’s state space. The system is completely described by its state vector, which is a unit vector in the system’s state space.
  
-**2.** The evolution of a closed quantum system is described by a unitary transformation. +**2.** The evolution of a closed quantum system is described by a [[topic:math:linalg:operator|unitary]] transformation. 
 That is, the state $\ket{\psi}$ of the system at time t1 is related to the state $\ket{\psi'}$ of the system at time t2 by a unitary operator U which depends only on the times t1 and t2, $\ket{\psi'} = U \ket{\psi}$ That is, the state $\ket{\psi}$ of the system at time t1 is related to the state $\ket{\psi'}$ of the system at time t2 by a unitary operator U which depends only on the times t1 and t2, $\ket{\psi'} = U \ket{\psi}$
  
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 H is a fixed Hermitian operator known as the //Hamiltonian// of the closed system. H is a fixed Hermitian operator known as the //Hamiltonian// of the closed system.
  
-**3.** Quantum measurements are described by a collection ${M_m}$ of measurement operators. +**3.** [[topic:qm:measurements|Quantum measurements]] are described by a collection ${M_m}$ of measurement operators. 
 These are operators acting on the state space of the system being measured.  These are operators acting on the state space of the system being measured. 
-The index m refers to the measurement outcomes that may occur in the experiment. +The index $mrefers to the measurement outcomes that may occur in the experiment. 
 If the state of the quantum system is $\ket{\psi}$ immediately before the measurement then the probability that result $m$ occurs is given by If the state of the quantum system is $\ket{\psi}$ immediately before the measurement then the probability that result $m$ occurs is given by
 $$p(m) = \Braket{\psi | M_m^\dag M_m | \psi}$$ $$p(m) = \Braket{\psi | M_m^\dag M_m | \psi}$$
topic/qm/postulates.1670613074.txt.gz · Last modified: by samuel