Quantum Computing
It all began in 1981 with Richard P. Feynman quoting “ Can we simulate physics on a computer?” Well, though quite intriguing but answer to that question as of right now is obviously no and the only reason for that is a significant part of physics is Quantum physics which can’t be simulated on the computers present today, ie, the classical computers.
Lets see why. Say we have a system comprising of 30 particles. Now in Quantum physics we have variables to define a state of a particle. Consider that two variables are associated with a particle then , corresponding to 30 particles we’ll have 230 variables . That amount of data can be stored with present computers. But what if number of particles go beyond say 100. Correspondingly we’ll have 2100 variables. Now this can’t be simulated on a classical computer , since they don’t have this much memory and they never will !
Feynman suggested “ One can turn problem into an effect “. If Quantum physics is too rough for present computers may be we can use it to build better computers!
Lets see a computing perspective.
One person who has been looking at the miniaturization of computers is Gordon Moore, also the co-founder of intel back in 1960’s. He predicted that number of components on a chip doubles every 18 months to two years. Therefore, the smallest feature size on the Si chip has to decrease at the same rate. Hence, the Moore’s law. What’s amazing about Moore’s law is that you can predict what’s going to happen in time. Now, If we follow this law , less than 10 years from now, ie, as we approach 2020 , the size of transistor will reduce to the size of an atom- the smallest component of nature. Thereby , here we enter the Quantum realm.
Hence either way Quantum computing is inevitable future of computing.
Lets see why. Say we have a system comprising of 30 particles. Now in Quantum physics we have variables to define a state of a particle. Consider that two variables are associated with a particle then , corresponding to 30 particles we’ll have 230 variables . That amount of data can be stored with present computers. But what if number of particles go beyond say 100. Correspondingly we’ll have 2100 variables. Now this can’t be simulated on a classical computer , since they don’t have this much memory and they never will !
Feynman suggested “ One can turn problem into an effect “. If Quantum physics is too rough for present computers may be we can use it to build better computers!
Lets see a computing perspective.
One person who has been looking at the miniaturization of computers is Gordon Moore, also the co-founder of intel back in 1960’s. He predicted that number of components on a chip doubles every 18 months to two years. Therefore, the smallest feature size on the Si chip has to decrease at the same rate. Hence, the Moore’s law. What’s amazing about Moore’s law is that you can predict what’s going to happen in time. Now, If we follow this law , less than 10 years from now, ie, as we approach 2020 , the size of transistor will reduce to the size of an atom- the smallest component of nature. Thereby , here we enter the Quantum realm.
Hence either way Quantum computing is inevitable future of computing.
A quantum Computer computes according to the Quantum mechanics. It encodes information into quantum particles, manipulates them and computes by measuring their resultant state probability.
Instead of bits we use Quantum bits(also known as Qubits) in a quantum computer. Qubits are basically two
state quantum systems. For example say I’ve a Hydrogen atom and given that its electron can be in either Ground state or first excited state or any superposition of two. This represents a qubit. Other examples of qubits are Atomic Orbitals, Polarized photons and Electronic spins.
Other two important principles governing the working of a quantum computer are :
Quantum Parallelism and Quantum Interference. Quantum parallelism is used to perform computations at the same time and Quantum Interference is used to combine results into one.
Applications
There are some problems out there that just can’t be solved using our classical computers.
For example , lets take a very prominent classroom problem, Traveling Salesman problem.
Now problem is : A salesman has to travel many cities and workout short test possible route such that he makes back home in shortest time.
As the number of cities increase , the number of routes increase exponentially. Say for 14 cities the number of routes reach 1011. For a classical 1GHz computer (109 operations per second) , it will take 100 secs. But for 22 cities, 1019 routes , it’ll take 1600 years! And for 28 cities , the time span is even longer than the lifetime of the universe!
The Quantum computers power rises exponentially every time we increase the qubit count . For 30 Qubits, it would be more powerful than a super computer and for 300 Qubits , It would be more powerful than all the computers of the world connected together. Just imagine 300 Qubits vs 3 billion transistors which are present on a Si chip today. That’s the power of Quantum computation.
Other Applications includes :
- Faster Code Breaking
-Useful to Scientists for Virtual experiments
-Problems with enormous amount of data and calculations like space problems.
- Cryptography
Another common Application is that say we have 1 billion numbers and we need to find two equal numbers among them (Say searching a name corresponding to a number in a phonebook). A normal Computer will take so many steps while a Quantum Computer will be able to solve that problem very quickly.
Limitations
Though University of Innsbruck , Austria claims to have built a prototype of Quantum Computer named as Ion Trap. It works on 14 ions . But then again its a big challenge to scale up the technology from just 14 ions to thousands of particles. And that controlling that every single particle with very high precision.
A quantum computer can only function if the information exists for long enough to be processed. The so-called coherence of the qubit ensures that the quantum information remains intact. The researchers have now discovered that the coherence spontaneously disappears over the course of time and with this the stored information as well. This could pose a considerable problem for the development of a quantum computer.
A quantum computer makes use of the fact that a quantum mechanical system -an electron, an atom or even a larger system such as a superconducting quantum bit - can simultaneously exist in two states. Normally one of the two states disappears as soon as the system comes into contact with the outside world. The coherence then disappears as a result of the decoherence process and the information in a quantum bit is lost.
Instead of bits we use Quantum bits(also known as Qubits) in a quantum computer. Qubits are basically two
state quantum systems. For example say I’ve a Hydrogen atom and given that its electron can be in either Ground state or first excited state or any superposition of two. This represents a qubit. Other examples of qubits are Atomic Orbitals, Polarized photons and Electronic spins.
Other two important principles governing the working of a quantum computer are :
Quantum Parallelism and Quantum Interference. Quantum parallelism is used to perform computations at the same time and Quantum Interference is used to combine results into one.
Applications
There are some problems out there that just can’t be solved using our classical computers.
For example , lets take a very prominent classroom problem, Traveling Salesman problem.
Now problem is : A salesman has to travel many cities and workout short test possible route such that he makes back home in shortest time.
As the number of cities increase , the number of routes increase exponentially. Say for 14 cities the number of routes reach 1011. For a classical 1GHz computer (109 operations per second) , it will take 100 secs. But for 22 cities, 1019 routes , it’ll take 1600 years! And for 28 cities , the time span is even longer than the lifetime of the universe!
The Quantum computers power rises exponentially every time we increase the qubit count . For 30 Qubits, it would be more powerful than a super computer and for 300 Qubits , It would be more powerful than all the computers of the world connected together. Just imagine 300 Qubits vs 3 billion transistors which are present on a Si chip today. That’s the power of Quantum computation.
Other Applications includes :
- Faster Code Breaking
-Useful to Scientists for Virtual experiments
-Problems with enormous amount of data and calculations like space problems.
- Cryptography
Another common Application is that say we have 1 billion numbers and we need to find two equal numbers among them (Say searching a name corresponding to a number in a phonebook). A normal Computer will take so many steps while a Quantum Computer will be able to solve that problem very quickly.
Limitations
Though University of Innsbruck , Austria claims to have built a prototype of Quantum Computer named as Ion Trap. It works on 14 ions . But then again its a big challenge to scale up the technology from just 14 ions to thousands of particles. And that controlling that every single particle with very high precision.
A quantum computer can only function if the information exists for long enough to be processed. The so-called coherence of the qubit ensures that the quantum information remains intact. The researchers have now discovered that the coherence spontaneously disappears over the course of time and with this the stored information as well. This could pose a considerable problem for the development of a quantum computer.
A quantum computer makes use of the fact that a quantum mechanical system -an electron, an atom or even a larger system such as a superconducting quantum bit - can simultaneously exist in two states. Normally one of the two states disappears as soon as the system comes into contact with the outside world. The coherence then disappears as a result of the decoherence process and the information in a quantum bit is lost.
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