quantum physics

posted by Anonymous

8(a) Consider a spin qubit in the state 3ã2|0⟩+12|1⟩. What are the coordinates (ƒÆ,ϕ) of this qubit on the Bloch sphere?
Į=?
ϕ=?

8b. We turn on a magnetic field in the z^ direction at time t=0. This corresponds to the Hamiltonian H=BZ, where B is a constant and Z is the usual phase flip. What is the state of our qubit at time t as a function of B and t?

8c. What are the coordinates (ƒÆ,ϕ) of this qubit on the Bloch sphere at time t, as a function of B and t?

8d. Now suppose we start with the qubit |ƒÕ(0)⟩=|0⟩ and we apply a magnetic field in the x^ direction at t=0. This corresponds to the Hamiltonian H=BX, where B is a constant and X is the usual bit flip gate. What are the coordinates (ƒÆ,ϕ) of this qubit on the Bloch sphere at time t, as a function of B and t?
Į=?
ϕ=?

  1. Anonymous

    please help!!

  2. david

    D
    Į = 2Bt
    phi = pi/2

    C - pi/3; 2*B*t

    do you need explanation ?

  3. Anonymous

    @ David thanks but its wrong for d.

  4. Anonymous

    can you explain..please

  5. ss01

    try Į = 2Bt
    and phi = 0

  6. david

    sorry for that
    @ss01 your phi is wrong that i am for sure it cannot be 0

  7. david

    got my error
    8d ƒÆ= 0 and ϕ = 2bt
    check and tell me if i am right?
    8a ƒÆ = pi/3 and ϕ = 0

  8. stuart

    r u right,david abt 8d?

  9. stuart

    r u right,david abt 8d?and wat abt 8 b?

  10. david

    ya, this time

  11. david

    doing 8b

  12. stuart

    its wrong.8 d,

  13. Anonymous

    please help with 8d!!

  14. Anonymous

    8b:
    e^(-i*B*t)*sqrt(3)/2
    e^(i*B*t)/2

    please help with Q8D please

  15. Tu papi

    8D
    θ= 2⋅B⋅t
    ϕ= 3⋅π/2

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