Editing Quantum Computing (section)

==Quantum Computing==  

===What's this about?===

This paper reviews quantum computing and the connections between classical information theory, computer science, and quantum physics. 

===Quantum States Store Information=== 

In quantum mechanics, the state vector contains complete information about a system. This concept links quantum mechanics and information theory.

===Limits of Classical Computers===

Classical computers likely can't simulate all physical systems, since they can't produce Bell inequality-violating correlations.

===Quantum Cryptography===

Simple properties like measurement disturbance enable quantum cryptography. This was an early link between quantum mechanics and information.

===The Quantum Computer Concept===

The quantum computer depends on controlling quantum evolution to manipulate information in new ways. Key ideas include qubits, quantum gates, no cloning, and entanglement as a resource.

===Quantum Algorithms===

Algorithms like Shor's show quantum computers can be more efficient for some problems. Grover's algorithm speeds up unstructured search.

===Experimental Systems===

Ion traps and NMR are current experimental methods to implement small quantum information processors. Larger universal quantum computers remain challenging. 

===Quantum Error Correction===

Error correction methods like entanglement purification and stabilizer codes can protect quantum information from noise and errors. This makes reliable quantum computing seem more feasible.

===Conclusion=== 

Quantum information theory provides new insights into physics and expands our conception of how information can be processed. There are still many open questions, but quantum mechanics and information go hand in hand.

===Key References===

- Bennett & Wiesner 1992 
- Ekert 1991
- Deutsch 1985
- Shor 1994
- Cirac & Zoller 1995
- Steane 1996