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Quantum Computing. U f. Nick Bonesteel. H. H. Discovering Physics, Nov. 16, 2012. q. H. f. What is a quantum computer, and what can we do with one?. A Classical Bit: Two Possible States. 0. A Classical Bit: Two Possible States. 1. Single Bit Operation: NOT. NOT. x y 0 1
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Quantum Computing Uf Nick Bonesteel H H Discovering Physics, Nov. 16, 2012 q H f
Single Bit Operation: NOT NOT x y 0 1 1 0 y x 0
Single Bit Operation: NOT NOT x y 0 1 1 0 y x 1
A Quantum Bit or “Qubit” Quantum superposition of 0 and 1 0 1
A Quantum Bit: A Continuum of States q 0 1 cos sin q q +
q q - f + i cos 0 sin e 1 2 2 A Quantum Bit: A Continuum of States Actually, qubit states live on the surface of a sphere. q f
A Quantum Bit: A Continuum of States But the circle is enough for us today. q 0 1 cos sin q q +
X A Quantum NOT Gate
X X A Quantum NOT Gate
X A Quantum NOT Gate
X X A Quantum NOT Gate
H H Hadamard Gate
H H Hadamard Gate
H H Hadamard Gate
H H Hadamard Gate
H H Hadamard Gate H is its own inverse
H H Hadamard Gate H is its own inverse
H H Hadamard Gate H is its own inverse
H H Hadamard Gate H is its own inverse
Fair Coin Trick Coin
Balanced Function or Unbalanced Function or
Uf A Two QubitSubroutine to Evaluate f(x)
Uf A Two QubitSubroutine to Evaluate f(x) Input x can be either 0 or 1 Output is f(x) Initialize to state “0”
Uf A Two QubitSubroutine to Evaluate f(x) Input x can be either 0 or 1 This qubit can also be in state “1”
Uf A Two QubitSubroutine to Evaluate f(x) Input x can be either 0 or 1 Bar stands for “NOT” This qubit can also be in state “1” 0 = 1, 1 = 0
Uf Uf A Two QubitSubroutine to Evaluate f(x) Unbalanced Balanced or or
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H Only ran Uf subroutine once, but f(0) and f(1) both appear in the state of the computer!
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H If f is balanced: f(0) = f(1) and f(0) = f(1)
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H If f is balanced: f(0) = f(1) and f(0) = f(1)
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H If f is balanced: f(0) = f(1) and f(0) = f(1)
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H If f is unbalanced: f(0) = f(1) and f(0) = f(1)
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H If f is unbalanced: f(0) = f(1) and f(0) = f(1)
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H If f is unbalanced: f(0) = f(1) and f(0) = f(1)
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H Balanced: Unbalanced:
Uf A Quantum Algorithm (Deutsch-Jozsa ‘92) H H H Balanced: Unbalanced: