quantum measurement has the effect of ‘‘magnifying’’

one of the outcomes of quantum superposition

probabilistic, sequential

Only at this point do indeterminacy and probabilities

E.T.

QUANTUM WORLD CLASSICAL WORLD

Quantum computation is

deterministichighly (exponentially) parallel

unitary

described by Schrodinger equationusing entanglement as a computational

resource

quantumcomputation(evolution)

Classical computation is

working with real probabilities

of computation are irreversibly lost

MEAS

UREM

ENT

come in

quantum events from quantum to classical level..

working with complex

is randomly picked up - all other results amplitudes

(b) (c)(a)

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??

?

?

?

??

? ??

y

x

z

(a)

(b)

(c)

(d)

A B

cat

observer

E. T.

source

switch switch

A

B

C

D

a b c d e f g h g f e d c b

finitecontrol

tape

q

k tapes

q

q?

x

x in A ? ORACLE

oracle-tape

oracle-tape

for A

c

c c c

c c c c c c c c

0

1 2 3

4 5 6 7 8 9 10 11

12 3

1 2 3 4 1 1 2 3

c

c c

c c c c c

0.6 0.4

1 2

3 4 5 6 7

0

0.5 0.5

0.3 0.50.2

q

a b c d e f g h i j k l m n

00101101

01

0 tapeof randombits

finite control

read-write tape

configuration tree

(a) (b)