Knowee
Questions
Features
Study Tools

Assume we had a particle which initially was at position ๐‘…๐‘–โƒ—R iโ€‹ โ€‹ . Now, after time ๐‘กt has passed, what is the probability of finding that particle in a position ๐‘…๐‘“โƒ—R fโ€‹ โ€‹ ?โŸจ๐‘…๐‘–โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ R iโ€‹ โ€‹ โˆฃU(t)โˆฃ R iโ€‹ โ€‹ โŸฉโŸจ๐‘…๐‘“โƒ—โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ๐‘…๐‘–โƒ—โˆฃ๐‘…๐‘“โƒ—โŸฉโŸจ R fโ€‹ โ€‹ โˆฃ R iโ€‹ โ€‹ โŸฉโŸจ R iโ€‹ โ€‹ โˆฃ R fโ€‹ โ€‹ โŸฉโŸจ๐‘…๐‘“โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ R fโ€‹ โ€‹ โˆฃU(t)โˆฃ R iโ€‹ โ€‹ โŸฉโŸจ๐‘…๐‘“โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ๐‘…๐‘–โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘“โƒ—โŸฉโŸจ R fโ€‹ โ€‹ โˆฃU(t)โˆฃ R iโ€‹ โ€‹ โŸฉโŸจ R iโ€‹ โ€‹ โˆฃU(t)โˆฃ R fโ€‹ โ€‹ โŸฉโŸจ๐‘…๐‘“โƒ—โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ R fโ€‹ โ€‹ โˆฃ R iโ€‹ โ€‹ โŸฉ

Question

Assume we had a particle which initially was at position ๐‘…๐‘–โƒ—R iโ€‹ โ€‹ . Now, after time ๐‘กt has passed, what is the probability of finding that particle in a position ๐‘…๐‘“โƒ—R fโ€‹ โ€‹ ?โŸจ๐‘…๐‘–โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ R iโ€‹ โ€‹ โˆฃU(t)โˆฃ R iโ€‹ โ€‹ โŸฉโŸจ๐‘…๐‘“โƒ—โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ๐‘…๐‘–โƒ—โˆฃ๐‘…๐‘“โƒ—โŸฉโŸจ R fโ€‹ โ€‹ โˆฃ R iโ€‹ โ€‹ โŸฉโŸจ R iโ€‹ โ€‹ โˆฃ R fโ€‹ โ€‹ โŸฉโŸจ๐‘…๐‘“โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ R fโ€‹ โ€‹ โˆฃU(t)โˆฃ R iโ€‹ โ€‹ โŸฉโŸจ๐‘…๐‘“โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ๐‘…๐‘–โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘“โƒ—โŸฉโŸจ R fโ€‹ โ€‹ โˆฃU(t)โˆฃ R iโ€‹ โ€‹ โŸฉโŸจ R iโ€‹ โ€‹ โˆฃU(t)โˆฃ R fโ€‹ โ€‹ โŸฉโŸจ๐‘…๐‘“โƒ—โˆฃ๐‘…๐‘–โƒ—โŸฉโŸจ R fโ€‹ โ€‹ โˆฃ R iโ€‹ โ€‹ โŸฉ

...expand
๐Ÿง Not the exact question you are looking for?Go ask a question

Solution

The question seems to be asking for the probability of finding a particle at a certain position after a certain time has passed, given its initial position. This is a common question in quantum mechanics, and the answer involves the time evolution operator U(t).

The probability amplitude of finding the particle at position ๐‘…๐‘“โƒ— after time t, given that it started at position ๐‘…๐‘–โƒ—, is given by the matrix element โŸจ๐‘…๐‘“โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉ. This is the overlap of the state |๐‘…๐‘–โƒ—โŸฉ evolved forward in time by U(t) with the state |๐‘…๐‘“โƒ—โŸฉ.

The probability is then given by the absolute square of this amplitude, i.e., |โŸจ๐‘…๐‘“โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉ|^2.

Note that โŸจ๐‘…๐‘–โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉ is the probability of the particle remaining at the initial position after time t, and โŸจ๐‘…๐‘“โƒ—โˆฃ๐‘…๐‘–โƒ—โŸฉ and โŸจ๐‘…๐‘–โƒ—โˆฃ๐‘…๐‘“โƒ—โŸฉ are the overlaps of the initial and final states, which are generally not relevant for this calculation unless the states are not normalized.

Also, โŸจ๐‘…๐‘“โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘–โƒ—โŸฉ and โŸจ๐‘…๐‘–โƒ—โˆฃ๐‘ˆ(๐‘ก)โˆฃ๐‘…๐‘“โƒ—โŸฉ are generally not equal because U(t) is not necessarily a Hermitian operator, so the order of the states matters.

This problem has been solved

Similar Questions

When a probabilistic bit is in (10)(10) , we apply the operatorย (1/21/201)(1/201/21) ย three times.ย What is the probability of being in stateย  โŒˆ1โŒ‹โŒˆ1โŒ‹ย  ย at the end?

When a probabilistic bit is in (10)(10) , we apply the operatorย (1/21/201)(1/201/21) ย three times.ย What is the probability of being in stateย  โŒˆ1โŒ‹โŒˆ1โŒ‹ย  ย at the end?Group of answer choices3/41/87/81/21/4

Choose the correct sentence.The probability of finding the quantum particle in a volume ๐‘‘๐‘‰dV at a point (๐‘ฅ,๐‘ฆ,๐‘ง)(x,y,z) at time ๐‘กt is given by โˆฃ๐œ“(๐‘ฅ,๐‘ฆ,๐‘ง;๐‘ก)โˆฃ2โˆฃฯˆ(x,y,z;t)โˆฃ 2 .The probability of finding the quantum particle in a volume ๐‘‘๐‘‰dV at a point (๐‘ฅ,๐‘ฆ,๐‘ง)(x,y,z) at time ๐‘กt is given by ๐œ“(๐‘ฅ,๐‘ฆ,๐‘ง;๐‘ก)๐œ“โ‹†(๐‘ฅ,๐‘ฆ,๐‘ง;๐‘ก)๐‘‘๐‘‰ฯˆ(x,y,z;t)ฯˆ โ‹† (x,y,z;t)dV.๐œ“(๐‘ฅ,๐‘ฆ,๐‘ง;๐‘ก)ฯˆ(x,y,z;t) is the probability of finding the particle at the given time and position.

6.Question 6Suppose we have a particle in 1-dimension, with wavefunction ๐ด๐‘’โˆ’โˆฃ๐‘ฅโˆฃ2๐‘‘Ae โˆ’ 2dโˆฃxโˆฃโ€‹ .What is the probability to find the particle in the interval [0,๐‘‘][0,d]?Please provide your answer in terms of ๐ดA, ๐‘‘d, mathematical constants such as ๐œ‹ฯ€ (entered as 1pi) or ๐‘’e (entered as 1e).(Assume that A is real)1 point0.5*(1-e^-1)A^2*d*(1-exp(-1))A^2*d*(1-e^-1)0.5*(1-exp(-1))

The original probability is an unconditional probability called a '' probability, in the sense that it reflects only what we know now before the arrival of any new information.

1/1

Upgrade your grade with Knowee

Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.