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March 26, 2017

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Suppose we ran m steps of Grover's algorithm on some function f (which has one marked element y) and the resulting superposition was exactly |y⟩.
If we run for m+1 additional steps (i.e. total of 2m+1 steps from the initial state), what is the resulting superposition? Note that you can describe the superposition by specifying two numbers, αy and αx for x≠y. You may use K to denote the total number of elements. (K should be uppercase.) HINT: You may want to review Problems 2, 3, and 5 of Assignment 6.
αy :
αx for x≠y:
Now if we run for another m steps, what is the resulting superposition?
αy :
αx for x≠y:
What about after yet another m+1 steps?
αy :
αx for x≠y:

  • Quantum Physics - ,

    Stucklike you :(, anyone please

  • Quantum Physics - ,

    I have done 6A:
    (1/2 5/2)
    (5/2 1/2)

    6C and 6D: 0

    others pleasee

  • Quantum Physics - ,

    6B is
    (1/sqrt(2))*(e^(-3*i*t)) and (1/sqrt(2))*(e^(2*i*t))

  • Quantum Physics - ,

    6B: exp(-3it/sqrt(2)|+> and exp(2it/sqrt(2)|->

  • Quantum Physics - ,

    Problem 5 plz

  • Quantum Physics - ,

    Thank you guys!!

  • Quantum Physics - ,

    4b= 4

    someone for the first??plzz

  • Quantum Physics - ,

    Any kind of help is well received ;)

  • Quantum Physics - ,

    3C=0

  • Quantum Physics - ,

    1st is part c):

    -z-h-
    -x-h-

  • Quantum Physics - ,

    3B is Z

  • Quantum Physics - ,

    I meant answer to question 1 is part c.

    -z-h-
    -x-h-

  • Quantum Physics - ,

    problem 5,7 please.

  • Quantum Physics - ,

    4A please

  • Quantum Physics - ,

    problem 4 a):

    the eigenvalues are 1 and -1

    then the lowest eingevalue (ground energy) is : -1

  • Quantum Physics - ,

    4A is -1

  • Quantum Physics - ,

    3D yes or no ?

  • Quantum Physics - ,

    3d no

  • Quantum Physics - ,

    Problem 7a
    theta = pi/4
    phi = 5*pi/2

  • Quantum Physics - ,

    Problem 7b
    1/2+i/2
    1/sqrt(2)

  • Quantum Physics - ,

    wrong

  • Quantum Physics - ,

    7A and 7B wrong

  • Quantum Physics - ,

    SOMEBODY KNOW ANSWER FOR: 3A? 5? 7? 2? 4C?

  • Quantum Physics - ,

    5 and 7 please

  • Quantum Physics - ,

    hikikomori, do you have answer for the 3A? 5? 7? 2? 4c?

  • Quantum Physics - ,

    hikikomori,Sorry, do you have answer for the 3A? 2? 4c?

  • Quantum Physics - ,

    7A) pi/2 , 5*pi/4

  • Quantum Physics - ,

    7B) 0.707 , -0.5-(0.5*i)

  • Quantum Physics - ,

    5?

  • Quantum Physics - ,

    4C (001, 010, 100, 111)

  • Quantum Physics - ,

    anyone question 5?

  • Quantum Physics - ,

    3A: C option

  • Quantum Physics - ,

    Thanks all guys.
    We now just need Q5's answers.

  • Quantum Physics - ,

    We need Q.2 also

  • Quantum Physics - ,

    for 2, last option is correct

  • Quantum Physics - ,

    Thanks all guys
    well-done

  • Quantum Physics - ,

    Problem 5 please?

  • Quantum Physics - ,

    desperately need answer for question 5. can someone explain a little how we get last option as correct for problem 2. as in the original cct if we give input 1> and 0> then apply cnot then we get 11> as the target bit flips.after that once apply Z gate (which will now be 4x4 matrix)we obatain (0,-1,0,1). how last option satisfy the same with same input as 0> once pass Z gate we get same 0> later as control bit is 1> it flips it after application of cnot and we get 11> as output. how are both equivalent??plz help

  • Quantum Physics - ,

    Anyone??? Pls Q5... guys do soething pls

  • Quantum Physics - ,

    PLease Problem 5!?

  • Quantum Physics - ,

    5A: (2/K - 1), (2/K)

    5B: (1- 2/K), (-2/K)

    5C: (2/K - 1), (2/K)

  • Quantum Physics - ,

    EdX Winner its wrong answer

  • Quantum Physics - ,

    5A: (2/K), (1 - 2/K)

    5B: (-2/K), (2/K - 1)

    5C: (2/K - 1), (-2/K)

  • Quantum Physics - ,

    Wrong? It worked for me!

  • Quantum Physics - ,

    qwerty urs answer is also showing wrong dude

  • Quantum Physics - ,

    All wrong?

  • Quantum Physics - ,

    YES ALL WRONG

  • Quantum Physics - ,

    the above answers to 5th question is of assignment 6 problem 5 don't get misguided

  • Quantum Physics - ,

    Anon.. What is the correct answer to the 5? please help us

  • Quantum Physics - ,

    WORKING ON IT AR . DISTRACTED BY SOME PERSONAL PROBLEMS IN LIFE ... NOT ABLE TO CONCENTRATE

  • Quantum Physics - ,

    I think it should look like

    (k-2)^x + ...
    -------------
    k^x

    where x = m+1
    but i have failed for find oput more :-(

  • Quantum Physics - ,

    I am trying my best. Cant seem to get an answer. I will keep trying. Till then, I request others to try and post solutions here as well. Thanks.

  • Quantum Physics - ,

    In the assignment 6, when you look to the posted answer it was written -answer to the part (c)- "Note that this is exactly the negation of the answer to part (a)". I think the following:
    the state after " m+p steps + phase inversion" is equal to minus (-) the state after m-p steps! I checked this statement and it turns out to be true: the state after "2m step + phase inversion" must be equal to minus (-) the initial state...however when I enter the answer which becomes obvious when you apply the above observation, the grader says always "wrong"!...so guys to be honest with you: I still have only one shot for the three questions of problem 5: so or I get them all right (and for sure I will forward the right answer to all of you) or I will get them wrong...bye bye

  • Quantum Physics - ,

    problem 3b,4c and 5

  • Quantum Physics - ,

    well guys, i need few drinks (i'm doing my best MF) and we will be all right..cheer MF

  • Quantum Physics - ,

    Some ppl think there is a simple answer to the problem.
    To be honest I do not beleive it. For instance let m=1 and k=171. Why not? The original state was not defined in the problem, so it just might be that way. Will the "answer" work? I am sure it won't.

  • Quantum Physics - ,

    Hi! I have just done 5B: ay=-1, ax=0, so, cheers and PhysTech, it must something about a cycle of the states from m-2, m-1, m, m+1, m+2

  • Quantum Physics - ,

    Hi J. If the grader thinks it is the proper answer it doesn't mean it is. I tried it for a several k and there is no cicle except fo k=2. Try for k=7, and goes and goes without end, never in cicle.

  • Quantum Physics - ,

    @xaad

    3B: Z (3rd option)
    4C: Last option
    5B: ay = -1; ax = 0
    5A, 5C: ---Not yet solved correctly---

  • Quantum Physics - ,

    Hi PhysTech, I am reading an article from twistedoakstudios(at)com in /blog/Post2644_grovers-quantum-search-algorithm and doing some calculations... Seems cyclic, in a geometric view.

  • Quantum Physics - ,

    Ok, 5C is 1/sqrt(K) for both of them. I cannot figure out what is 5A... :(

  • Quantum Physics - ,

    5A is not -1/sqrt(N) or any combinations with minus sign.

  • Quantum Physics - ,

    @J
    I input 1/sqrt(K) as 5C's answer, but they are wrong.

  • Quantum Physics - ,

    @J
    No they're right, I misspell the answer

  • Quantum Physics - ,

    dudes there is something wrong with the system: i did not answer to 5) c) and as I mentioned before I have a last shot (only one shot) and guess what? I gave the answer to 5)b) (which was -1 and 0) and automatically the grader gave me the answer for 5)c)which is (1/sqrt(k),1/sqrt(k))...!!!!! there is something wrong here...don't you think so???

  • Quantum Physics - ,

    wow! Strange behaviour @cheers xD Nevertheless good news for 5C :D Now, only 5A remains behind the Fortress of Solitude...

  • Quantum Physics - ,

    @J "sorry I did not sleep the whole night"...I apologise to everybody...I'm still working on a) please forgive my "swearing" I did not sleep for 24h...booze make you thinking...cheers

  • Quantum Physics - ,

    C'mon @cheers!! get some rest :) 5A is not (0,-1), or (0,1/sqrt(K)) or (0,-1/sqrt(N)) xD It must be something very close to it... I think the answer is translating the grover algorithm to a Bloch Sphere and see how it moves around the surface :) At least, that is what 5B,c suggest me...

  • Quantum Physics - ,

    what is the answer of 6B?
    (1/sqrt(2))*(e^(-3*i*t)) and (1/sqrt(2))*(e^(2*i*t))

    or

    6B: exp(-3it/sqrt(2)|+> and exp(2it/sqrt(2)|->

  • Quantum Physics - ,

    Anonymous its the first.

    (1/sqrt(2))*(e^(-3*i*t)) and (1/sqrt(2))*(e^(2*i*t))

  • Quantum Physics - ,

    Anyone for Problem 5 a)?

  • Quantum Physics - ,

    Dear friends, I tried this:
    5c)(1/sqrt(k),1/sqrt(k))
    but doesnt work...
    Anyone for 5c and 5a???

  • Quantum Physics - ,

    uppercase K

  • Quantum Physics - ,

    5) a)?

  • Quantum Physics - ,

    Thank you!!

  • Quantum Physics - ,

    ANyone for 5)c)?

  • Quantum Physics - ,

    Meant 5) a)?
    Thank

  • Quantum Physics - ,

    5 a)?!

  • Quantum Physics - ,

    Gyus, 5 is easier than you think!
    It takes exactly m steps from starting superposition (ay = 1/sqrt(K), ax = 1/sqrt(k)) to get to the solution (ay = 1, ax = 0), then it takes exactly m+1 steps to get back to initial state, but after each cycle the sign changes!
    So it looks like this:
    0: ay = 1/sqrt(K), ax = 1/sqrt(k)
    m: ay = 1, ax = 0
    2m+1: ay = -1/sqrt(K), ax = -1/sqrt(k)
    3m+1: ay = -1, ax = 0
    4m+2: ay = 1/sqrt(K), ax = 1/sqrt(k)
    5m+2: ay = 1, ax = 0
    6m+3: ay = -1/sqrt(K), ax = -1/sqrt(k)
    ........

  • Quantum Physics - ,

    guess the right answer for 5a
    and don't forget to write CAPITAL K

  • Quantum Physics - ,

    It is this, thanks Andy!
    5)a)
    ay = -1/sqrt(K)
    ax = -1/sqrt(K)

  • Quantum Physics - ,

    thanks Andy,Flu and everyone worked for this subject!

  • Quantum Physics - ,

    thank you!!!

  • Quantum Physics - ,

    thx all!!

  • Quantum Physics - ,

    Well done Guys... Cheers 2 all...

  • Quantum Physics - ,

    Correct answers to 5A,5B,5C:

    5A:
    ay=-1/sqrt(K)
    ax=-1/sqrt(K)

    5B:
    ay=-1
    ax=0

    5C:
    ay=1/sqrt(K)
    ax=1/sqrt(K)

  • Quantum Physics - ,

    hey guys,i want the answer of Problem 2

  • Quantum Physics - ,

    Eisteinos

    2) answer is e

    ------*------
    |
    --Z---0------

  • Quantum Physics - ,

    Suppose we have a quantum circuit that takes the input |0> and outputs |+>, and also takes the input |1> and outputs −|−>. If we input √2*i/√3|+> + 1√3|−>, what does the circuit output?
    In the form a│0> + b│1>

  • Quantum Physics - ,

    what is the answer for q1?

  • Quantum Physics - ,

    1a. Z
    1b. X
    1c. X
    1d. D=Z
    1d. E=Z
    1e. Z
    1f. G=X
    1f. G'=X

  • Quantum Physics - ,

    Please Q 7 and 8!

  • Quantum Physics - ,

    8a- pi/3,o

  • Quantum Physics - ,

    8D please!

  • Quantum Physics - ,

    Anonymous, did you get all solutions for Q 7 and 8 except 8(D).
    If yes then please share......

  • Quantum Physics - ,

    @abc did you got question 8D?

  • Quantum Physics - ,

    thnx, all of you for your help

  • Quantum Physics - ,

    Someone made ​​the second, please?

  • Quantum Physics - ,

    Esta resposta para 2 esta correta? Como posso inserir esta questão?

    ------*------
    |
    --Z---0------

  • Quantum Physics - ,

    The answer to 2 is correct? How do I insert this?

    ------*------
    |
    --Z---0------

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