quantum information technology
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QUANTUM INFORMATIONTECHNOLOGY
PREPARED BY:FENNY
THAKRAR
DEFINITION
Quantum information theory is the study of how to integrate information theory with quantum mechanics, by studying how information can be stored with (and retrieved from) a quantum mechanical system.
QUANTUM INFORMATION TECHNOLOGY IS NOTHING BUT DEALING WITH COMPUTERS USING QUANTUM PHYSICS…
AND HENCE ITS ALSO CALLED QUANTUM COMPUTING…
WHAT IS QUANTUM COMPUTATION?
Computation with coherent atomic-scale dynamics.
The behavior of a quantum computer is governed by the laws of quantum mechanics.
THE POWER OF QUANTUM COMPUTATION…
In quantum systems possibilities count, even if they never happen! -like particle theory.
Each of exponentially many possibilities can be used to perform a part of a computation at the same time.
WHY BOTHER ABOUT QUANTUM COMPUTATION???
Moore’s Law: We hit the quantum level
2010~2020. Quantum computation is more
powerful than classical computation.
More can be computed in less time—the complexity classes are different!
QUBIT Digital systems have – bit Quantum systems have – qubit The primary piece of information in
quantum information theory is the qubit, an analog to the bit (1 or 0) in classical information theory.
The two position states of a photon in a Mach-Zehnder apparatus is just one example of a quantum bit or qubit
PARTICLE THEORY USED
The particle can exist in a linear combination or superposition of the two paths
This concept is applied here using qubits for computations.
QUANTUM GATES Quantum Gates are similar to classical
gates, but do not have a degenerate output. i.e. their original input state can be derived from their output state, uniquely. They must be reversible.
This means that a deterministic
computation can be performed on a quantum computer only if it is reversible.
QUANTUM PHYSICS CONCEPTS USED The following quantum physics concepts
are used in Quantum Computing. superposition Interference(constructive & destructive) Coherence Entanglement
1. SUPERPOSITION Superposition is a principle of
quantum theory
The principle of superposition claims that while we do not know what the state of any object is, it is actually in all possible states simultaneously.
Mathematically, it refers to a property of solutions to the Schrödinger equation
2.INTERFERENCE
In physics, interference is the phenomenon in which two waves superpose each other to form a resultant wave of greater or lower amplitude.
3. COHERENCE
In physics, coherence is a property of waves that enables stationary (i.e. temporally and spatially constant) interference.
4. ENTANGLEMENT
Entanglement is a term used in quantum theory to describe the way that particles of energy/matter can become correlated to predictably interact with each other regardless of how far apart they are.
APPLICATIONS OF QUANTUM COMPUTING
QUANTUM CRYPTOGRAPHYCRYPTOGRAPHY:-
Transmitting information with access restricted to the intended recipient even if the message is intercepted by others.
The process• Sender Plaintext
Cryptotext
Decryption
PlaintextRecipient
Message encryption
Key
Key ready for use
Secure key distribution
Encryption
Securetransmission
Hard Problem for conventionalencryption
THE CLASSIC CRYPTOGRAPHY Encryption algorithm and related
key are kept secret. Breaking the system is hard due to
large numbers of possible keys. For example: for a key 128 bits long
there are keys to
check using brute force. The fundamental difficulty is key
distribution to parties who want to exchange
messages.
38128 102
PKC – THE MODERN CRYPTOGRAPHY In 1970s the Public Key
Cryptography emerged. Each user has two mutually
inverse keys. The encryption key is published; The decryption key is kept
secret. Eg:- Anybody can send a
message to Bob but only Bob can read it.
RSA ALGO The most widely used PKC is the RSA
algorithm based on the difficulty of factoring a product of two large primes.
EASY PROBLEM:- Given two large primes p and q and compute
HARD PROBLEM:- Given n compute p and q.
qpn
FACTORING A PRODUCT OF TWO LARGE PRIMES The best known conventional
algorithm requires the solution time proportional to:
For p & q 65 digits long T(n) is approximately
one month using cluster of workstations
and For p&q 200 digits long T(n) is
astronomical.
])ln(ln)(lnexp[)( 3/23/1 nncnT
QUANTUM COMPUTING ALGORITHM FOR FACTORING In 1994 Peter Shor from the AT&T Bell
Laboratory showed that in principle a quantum computer could factor a very long
product of primes in seconds.
Shor’s algorithm time computational complexity is ])[(ln)( 3nOnT
THE MAIN CONTRIBUTION OF QUANTUM CRYPTOGRAPHY It solved THE KEY DISTRIBUTION
problem. It unconditionally secured the key
distribution method proposed by Charles Bennett and Gilles Brassard in 1984.
The method is called BB84.
QUANTUM KEY DISTRIBUTION
SECURITY OF QUANTUM KEY DISTRIBUTION
This makes impossible to intercept message without being detected.
WHATS THE NEED??!!?? Potential (benign) applications
- Faster combinatorial search - Simulating quantum systems
‘Spinoff’ in quantum optics, chemistry, etc.
Makes QM accessible to non-physicists Surprising connections between physics
and CS New insight into mysteries of the
quantum
GOALS & APPROACHES Key technical challenge:
prevent decoherence , or unwanted interaction with environment.
Approaches: NMR, ion trap, quantum dot,Josephson junction, opticals,etc….
THANK YOU !!!
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