one can never get over computers

1. PRESENTATION ON QUANTUM
COMPUTERS
FAST EFFICIENTAND POWERFUL MACHINESOF
FUTURE
BY:-
MONIKA
2K10/EP/028

2.  Lately, the key to improving computer performance has been the reduction of
size in the transistors used in modern processors. This continual reduction
however, cannot continue for much longer. If the transistors become much
smaller, the strange effects of quantum mechanics will begin to hinder their
performance. It would therefore seem that these effects present a fundamental
limit to our computer technology, or do they?The word "quantum" can conjure
up quite a few meanings. It's a reference to quantity. It's SPECTRE reborn for
the modern James Bond films. And it just sounds science-y in general thanks to
quantum dot displays, quantum mechanics and quantum entanglement.
Quantum computing may be the biggest buzzword of them all: it's an exciting
and extremely complex technology, and the science community's Top Men
have barely scratched the surface of it.
 A quantum computer is a device for computation that makes direct use
of quantum mechanical phenomena, such as superposition and entanglement,
to perform operations on data.Quantum computers perform operations with
qubits (quantum bits) rather than the binary bits of transistor-based computers
 The computing power of a quantum computer grows exponentially with its size
 A processor that can use registers of qubits will in effect be able to perform
calculations using all the possible values of the input registers simultaneously.
This phenomenon is called quantum parallelism, and is the motivating force
behind the research being carried out in quantum computing

3. QUBITS VS. BITS
 Let's start with regular bits. They're binary--meaning they represent 1 or 0, on
or off--and are used to perform calculations and represent information in
computers. Qubits are not binary. Thanks to the principle of quantum
superposition, quantum bits are both 0 and 1 simultaneously. Quantum
superposition states that a quantum element will only return a result in one state
when measured. Here a second principle comes into play: quantum
entanglement. Entanglement is actually how we "measure" the interaction of
electrons, molecules, photons, and other particles.
 Not only can a 'quantum bit', usually referred to as a 'qubit', exist in the classical 0
and 1 states, it can also be in a coherent superposition of both. When a qubit is
in this state it can be thought of as existing in two universes, as a 0 in one
universe and as a 1 in the other. An operation on such a qubit effectively acts on
both values at the same time. The significant point being that by performing the
single operation on the qubit, we have performed the operation on two different
values. Likewise, a two-qubit system would perform the operation on 4 values,
and a three-qubit system on eight. Increasing the number of qubits therefore
exponentially increases the 'quantum parallelism' we can obtain with the system.
With the correct type of algorithm it is possible to use this parallelism to solve
certain problems in a fraction of the time taken by a classical computer.

4. QUANTUM COMPUTERS COULD ONE DAY REPLACE SILICON CHIPS,
JUST LIKE THE TRANSISTOR ONCE REPLACED THE VACUUM TUBE.

5. QUANTUM ENTANGLEMENT
 The quantum entanglement is based on an idea that the tiny particles
can be connected with each other in such a way that change in state of
one affects the other, even if they happen to be miles apart.
 quantum computers encode data using this phenomenon
 Permanently links two objects
 So that each is affected by the experience of other no matter how far
they are
 Up till now entangled systems involving mainly photons or atomic
gases have been observed
 Called the entangled pair (EPR) : two bits at the price of one…..
 To achieve the unique feat the researchers made use of high powered
magnetic fields and super low temperatures to produce entanglement
between the electron and the nucleus of an atom. The atom that was
used was of the phosphorous element and it was embedded in a silicon
crystal.The entire phenomena is based on the magnet like behavior
shown by the nucleus and electrons of an atom.

6. QUANTUM CRYPTOGRAPHY
 The expected capabilities of quantum computation
promise great improvements in the world of
cryptography. Ironically the same technology also
poses current cryptography techniques a world of
problems. They will create the ability to break the
RSA coding system and this will render almost all
current channels of communication insecure

7. ADVANTAGES
 There are several reasons that researchers are working so hard to develop a practical quantum
computer. First, atoms change energy states very quickly -- much more quickly than even the
fastest computer processors. Next, given the right type of problem, each qubit can take the
place of an entire processor -- meaning that 1,000 ions of say, barium, could take the place of a
1,000-processor computer. The key is finding the sort of problem a quantum computer is able to
solve.
 If functional quantum computers can be built, they will be valuable in factoring large numbers,
and therefore extremely useful for decoding and encoding secret information. If one were to be
built today, no information on the Internet would be safe. Our current methods of encryption are
simple compared to the complicated methods possible in quantum computers. Quantum
computers could also be used to search large databases in a fraction of the time that it would
take a conventional computer.
 The theories of quantum computation suggest that every physical object, even the universe, is
in some sense a quantum computer. As Turing's work says that all computers are functionally
equivalent, computers should be able to model every physical process. Ultimately this suggests
that computers will be capable of simulating conscious rational thought. And a quantum
computer will be the key to achieving true artificial intelligence
 Quantum communication systems allow a sender and receiver to agree on a code without ever
meeting in person. The uncertainty principle, an inescapable property of the quantum world,
ensures that if an eavesdropper tries to monitor the signal in transit it will be disturbed in such a
way that the sender and receiver are alerted

8. DEVELOPMENTS IN THIS FIELD
 Quantum computing sounds like science fiction -as satellites,
moon shots, and the original microprocessor once were. But
the age of computing in not even at the end of the beginning.
 The julish supercomputer can now simulate the largest
quantum computer system in the world with 42 bits.
 Physicists Identify Room Temperature Quantum Bits in
Widely Used Semiconductor-The research team at UC
Santa Barbara discovered that silicon carbide contains crystal
imperfections that can be controlled at a quantum mechanical
level
 First quantum computer- University of Southern California
became the first academic institution to house an operational
quantum computer system on 28th october 2011. D-Wave One
Adiabatic Quantum Computer, the first commercially available
quantum computer

9. QUANTUM COMPUTERS COULD OVERTURN
HEISENBERG’S UNCERTAINTY PRINCIPLE
 The uncertainty principle is at the foundation of
quantum mechanics: You can measure a particle's
position or its velocity, but not both. Now it seems
that quantum computer memory could let us violate
this rule.
 A physicist Paul Dirac explained that one of the
very, very few ways to measure a particle's position
is to hit it with a photon and then chart where the
photon lands on a detector. That gives you the
particle's position, yes, but it's also fundamentally
changed its velocity, and the only way to learn that
would consequently alter its position

10. APPLICATIONS OF QUANTUM
COMPUTING
 Can solve sophisticated algorithms like Shor's algorithm
 Simulation of quantum mechanical systems - On classical computers,
the dynamics of a quantum system can be simulated using
approximations. A quantum computer however, can be "programmed" to
simulate the behaviour of a system by inducing interactions between its
variables. These imitate the characteristics of the system in question. A
quantum computer would, for example, allow the "Hubbard Model"
(which describes the movement of electrons within a crystal) to be
simulated, a task that is beyond the scope of current conventional
computers.
 Quantum Communication
 Artificial Intelligence
 Quantum Cryptography
Improved Error Correction and Error Detection Through similar processes that
support ultra-secure and super-dense communications, the existing bit streams
can be made more robust and secure by improvements in error correction and
detection. Recovering informational from a noisy transmission path will also be a
lucrative and useful practice.

11. CHALLENGES AHEAD
 The first is scalability - how do you build systems with large numbers of qubits
 The pitfall of quantum computing – decoherence -As soon as it measurable
interacts with the environment it will decohere and fall into one of the two
classical states. This is the problem of decoherence and is a stumbling block for
quantum computers as the potential power of quantum computers depends on
the quantum parallelism brought about by the coherent state. This problem is
compounded by the fact that even looking at a qubit can cause it to decohere,
making the process of obtaining a solution from a quantum computer just as
difficult as performing the calculation itself.
 A recent project from the University of California, Santa Barbara actually built a
rudimentary microprocessor using qubits, but it's a far cry from an Intel or AMD
chip
 the quantum computer's qubits only stay in an entangled state for 400
nanoseconds. That's 400 nanoseconds of operation--not exactly long enough to
substitute for the computers we use day in and day out. The current challenge is
not to build a full quantum computer right away but rather to move from the
experiments in which we merely observe quantum phenomena to experiments in
which we can control these phenomena. This is a first step towards quantum
logic gates and simple quantum networks

12. RESEARCHES GOING ON
 IBM has embarked upon a five year project to try its
hand at quantum computing.
 Researchers in quantum communication have enjoyed a
greater level of success. The partial quantum computers
involved have enabled secure communication over
distances as far as 10km
 A DARPA Quantum Network became fully operational on
Oct 23/03 in BBN’s laboratories, running the world’s first
Quantum Key Distribution (QKD) network using 24×7
quantum cryptography to provide unprecedented levels
of security for standard Internet traffic flows.
 Quantum computing is certainly 'on the radar' of IBM,
HP, and other supercomputing vendors, but it is difficult
to say how many engineers they have working on this
technology

13. CONCLUSION
 There's just one catch: it will be years, or even decades, before quantum computers can operate in place
of or alongside transistor-based computers.
 If someone makes a breakthrough in developing a fault-tolerant system with quantum error correction, it
might be time to get excited about quantum computing--that will be a Godzilla-sized step along the path
that ends in a genuinely usable machine.
 From a fundamental standpoint, however, it does not matter how useful quantum computation turns out to
be, nor does it matter whether we build the first quantum computer tomorrow, next year or centuries from
now.
 Some physicists are pessimistic about the prospects of substantial experimental advances in the field .
They believe that decoherence will in practice never be reduced to the point where more than a few
consecutive quantum computational steps can be performed. Others, more optimistic researchers,
believe that practical quantum computers will appear in a matter of years rather than decades. This may
prove to be a wishful thinking but the fact is the optimism, however naive, makes things happen. After all,
it used to be a widely accepted "scientific truth" that no machine heavier than air will ever fly.
 Although the future of quantum computing looks promising, we have only just taken our first steps to
actually realizing a quantum computer. There are many hurdles, which need to be overcome before we
can begin to appreciate the benefits they may deliver. Researchers around the world are racing to be the
first to achieve a practical system, a task, which some scientists think, is futile. David Deutsch - one of the
groundbreaking scientists in the world of quantum computing - himself said, "Perhaps, their most
profound effect may prove to be theoretical".

14. BIBLIOGRAPHY
 QUBIT.ORG
 WIKIPEDIA.ORG
 QUANTUM COMPUTING(STANFORD ENCYCLOPEDIA)
 Bennett, C. et al. (1997), ‘Strengths and weaknesses of quantum
computing’, SIAM Journal on Computing, 26(5): 1510–1523.
 SCIENCEDAILY.COM