This document provides a comprehensive overview of quantum computer architecture, detailing the history and development of quantum mechanics and its distinct features compared to classical mechanics. It explains key concepts such as qubits, quantum gates, and algorithms like Shor's and Grover's, highlighting their significance in advancing computational capabilities. Additionally, it addresses the challenges faced in quantum computing and future aspirations for improving qubit technology and operational efficiency.
Table of Contents
-History
- Classical vs Quantum Mechanics
- Breakdown of Classical Mechanics
- Quantum Mechanics Introduction
- Wave Function
- Quantum Bit (Qubit)
- Quantum Gates
- Quantum Computer
- Challenges
- Q & A
3.
Richard Feynman
“I thinkI can safely say that no one understand quantum mechanics!”
1982: Feynman
proposed the first
idea.
1985: Deutsch
developed the
quantum Turing
Machine.
1994: Shor
Algorithm to factor
very large numbers
in polynomial time.
1997: Grover
proposed a
quantum search
algorithm.
…Future!
3
4.
Classical Mechanics vsQuantum Mechanics
Mechanics: the study of the behavior of
physical bodies when subjected to forces or
displacements
Classical Mechanics: describing
the motion of macroscopic objects.
Macroscopic: measurable or
observable by naked eyes
Quantum Mechanics: describing
behavior of systems at atomic
length scales and smaller .
4
5.
Classical Mechanics
5
position r= (x,y,z)
velocity v
Property Behaviour
mass momentum
Particles position collisions
velocity
Waves wavelength diffraction
frequency interference
x
m
F
k
x = 0
k
m(d2x/dt2) = kx
+A
A
x
time period = 1/
position x(t) = Asin(t)
of particle
frequency = /2 =
(of oscillation)
m
π2
1 k
6.
Breakdown of ClassicalMechanics
6
ePhotelectrons-
h
Metal surface
work function = F
e
Photoelectrons ejected with
kinetic energy:
Ek = h - F
a) Black Body Radiation b) Photoelectric Effect
Max Planck (1900) Albert Einstein (1921)
7.
The Bohr Modelof the Atom
7
E = E2 E1 = h
h
E1
E2
h
E1
E2
Absorption Emission
n2
n1
e
p+
Niels Bohr, 1913
i
s
e
p=h/s
p=mev
i
s
cos1λλΔλ is
cm
h
e
The Compton Effect (1923) Electron Diffraction(1925)
8.
Partial Wave Duality
8
TwoSplit Experiment
t
tx
jtxxV
x
tx
m
),(
),()(
),(
2 2
22
Wave Function
(x,y,z) = (r) = (r,,)
9.
Bit vs QunatumBit (Qubit)
9
1 0
1
0
≡
≡
1
1
0
0
0
1
2221
1211
S=(Sφ Sθ SR=const)
• Two states classical bit
• Equalities
• Two levels quantum system (qubit)
• Single qubit operations
Polarization vector:
Density matrix:
//
)0()( iHtiHt
eet
10.
Computation with Qubit(I)
10
0 1
1 0
Classical Computation
Operations: logical
Valid operations:
AND =
0 i
-i 0
1 0
0 -1
1 1
1 -1
0 1
0
1
0 0
0 1
NOT =
0 1
1 0
in
out
out
in
in
1 0 0 0
0 1 0 0
0 0 0 1
0 0 1 0
1-bit
2-bit
Quantum Computation
Operations: unitary
Valid operations:
σX =
σy =
σz =
Hd =
CNOT =
√2
1
1-qubit
2-qubit
Quantum Algorithms (III)
17
Grover’sAlgorithm (1996)
n qubit
1qubit
Suppose we have a black box
with the property
Problem: find with as few queries as possible.
18.
Quantum Algorithms (V)
18
Grover’sAlgorithm
Repeated application of the Grover iterate
Grover’s algorithm:
1. start with
2. repeatedly apply Grover’s iterate to rotate to near
Quantum Computers Architecture(II)
21
• Ion traps and neutral atoms
E0
E1
E2
• Superconducting qubit
• Semiconductor charge qubit
• Spin qubit
Nuclear spin
(liquid state NMR,
solid state NMR)
I
Electron spin
S
SQUIDCooper pair box
Double QD
e
0 1
N pairs - 0 1N+1 pairs -
Single QD
F
i
E0
E1
e
• Photon based QC
P
0
1
Quantum Computers Architecture(IV)
23
Individual Photon
A
B
|1 = |0A|1B + |1A|0B
Quantum
Entanglement!
send single
photons
weak
laser
Ultraviolet ()
X
c(2) nonlinear crystal
24.
Quantum Computer Challenges
24
01
106 eV
CLASSICAL
|0
|1
10-6 eV
QUANTUM
- Dephasing
- Decoherence
- Control of Operations
- Isolation from environment
- Superpositions are very fragile!
25.
QC Future Works…
25
-More Qubits: 64, 128, 192, 256, …
- Much Greater Connectivity
- Much Lower Error Rate
- Much Longer Coherence
- True Fault Tolerance
- Much Lower Cost
- Non-cryogenic Operating
Temperature