n Consider Bell state of two qubits A and B, (10) A1) B+1) A|0) B)=(101) + |10)),

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Consider Bell state of two qubits A and B, (10) A1) B+1) A|0) B)=√(101) + |10)), and its corresponding density matrix p(+). We can think of 10) and 1) as spin-1/2 states [2+) and 2-), respectively. • Find density matrices pA = trв(p(+)), PB = trA(p(+)) Suppose a measurement of o₂ is performed on qubit B. Denote the probabilities of obtaining +1 and -1 as p+ and p_, respectively. What are p+ and p_? 12/+) = • If the result of a measurement on qubit B is +1, what is the two qubit state after the measurement? • Image we have a lot of pairs of qubits, each pair is prepared in state +). If observe B measure ₂ of qubit B. However, he does not announce or communicate his results. Another observer A has access to qubit A but not qubit B. Without learning B's results, she would have to treat her qubits as an ensemble PA = P+10A) (0₁| +P_1A) (14. Is there an experiment she can perform to tell whether B has made an measurement of σ₂? Consider Bell state of two qubits A and B, (10) A1) B+1) A|0) B)=√(101) + |10)), and its corresponding density matrix p(+). We can think of 10) and 1) as spin-1/2 states [2+) and 2-), respectively. • Find density matrices pA = trв(p(+)), PB = trA(p(+)) Suppose a measurement of o₂ is performed on qubit B. Denote the probabilities of obtaining +1 and -1 as p+ and p_, respectively. What are p+ and p_? 12/+) = • If the result of a measurement on qubit B is +1, what is the two qubit state after the measurement? • Image we have a lot of pairs of qubits, each pair is prepared in state +). If observe B measure ₂ of qubit B. However, he does not announce or communicate his results. Another observer A has access to qubit A but not qubit B. Without learning B's results, she would have to treat her qubits as an ensemble PA = P+10A) (0₁| +P_1A) (14. Is there an experiment she can perform to tell whether B has made an measurement of σ₂?

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