# quantum physics

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?
ƒÆ=?
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?
ƒÆ=?
ϕ=?

asked by Anonymous
1. please help!!

posted by Anonymous
2. D
ƒÆ = 2Bt
phi = pi/2

C - pi/3; 2*B*t

do you need explanation ?

posted by david
3. @ David thanks but its wrong for d.

posted by Anonymous
4. can you explain..please

posted by Anonymous
5. try ƒÆ = 2Bt
and phi = 0

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

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

posted by david
8. r u right,david abt 8d?

posted by stuart
9. r u right,david abt 8d?and wat abt 8 b?

posted by stuart
10. ya, this time

posted by david
11. doing 8b

posted by david
12. its wrong.8 d,

posted by stuart
13. please help with 8d!!

posted by Anonymous
14. 8b:
e^(-i*B*t)*sqrt(3)/2
e^(i*B*t)/2

please help with Q8D please

posted by Anonymous
15. 8D
θ= 2⋅B⋅t
ϕ= 3⋅π/2

posted by Tu papi

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