1. Quantum Computing Charles Bloomquist CS147 Fall 2009

2. What is a Quantum Computer? A quantum computer is a device for computation that makes direct use of distinctively quantum mechanical phenomena, such as superposition and entanglement, to perform operations on data.

3. Computation Comparison Classical Computation: ComputerComputationInputRulesOutput Quantum Computation: Physical system Motion Initial State Laws of Physics Final State

4. Quantum Information  A bit is the basic unit of computer information, is always either 0 or 1.  A quantum bit or qubit is the basic unit of information in a quantum computer, but unlike a classical bit it can be 0, 1, or a superposition of 0 and 1.  Superposition? Huh?

5. Quantum Superposition  A fundamental law of quantum mechanics.  It defines the collection of all possible states that an object can have simultaneously.  If you observe a qubit in superposition to determine its value the qubit will assume either a 0 or a 1 but not both.  This superposition of qubits is what gives quantum computers their inherent parallelism.  A 30-qubit quantum computer would equal the processing power of a conventional 10 teraflop computer.

6. Quantum Entanglement  Quantum phenomenon where two quantum particles become entangled.  The second particle will take on the properties of the first, even if the two particles are non-local.  This phenomenon allows us to know the value of the qubits without directly observing them.

7. Quantum logic gates  All quantum gates are reversible.  Controlled Gates  CNOT gate has the truth table of xor  Not Gate

8. Quantum algorithms  Shore’s algorithm can solve interger factorization problems in polynomial time.  Grover’s algorithm is used for searching unstructured database or unordered lists in only O(√N) queries instead of Ω(n).

9. What can it be used for?  Prime number factorization  Pattern matching/database searches  Code breaking  Quantum physics modeling

10. The 128-qubit computer  Dwave Systems introduced in December of 2008 Its Rainier computer (128 qubit) has a full 8-qubit unit cell. Dwave Systems Dwave Systems

11. References  David Deutsch video lectures on quantum computing. David Deutsch video lectures David Deutsch video lectures  How stuff works explains how quantum computing. How stuff works How stuff works  Obligatory Wikipedia on quantum:programming, computation, algorithm, superposition, and entanglement programmingcomputation algorithmsuperposition entanglementprogrammingcomputation algorithmsuperposition entanglement