Quantum computers
Quantum computers are machines that work with qubits (quantum bits) rather than regular bits.
Qubit
A regular bit is a transistor that registers either a high or low voltage, which corresponds to 1 or 0 respectively.
A quantum bit is a 2-state quantum “device.” Many things can be used as qubits, such as a photon’s horizontal and vertical polarization, or the spin up or spin down of an electron. What this means for us as computer scientists is that a qubit can be a 0, 1, or both.
Properties of qubit
Superposition: Superposition is the ability of a quantum system to be in multiple states at the same time until it is measured. When two wave fields are superposed their wave crests may add up.
Interference: When two quantum states interfere, the sates may cancel to reduce the states.
Entanglement — This is where one qubit’s state is linked to another. When entangled with each other, a change in one of the entangled qubits will change the other instantly.
One of the main properties of entanglement that helps quantum computation take a leap over classic binary operation is that The end state cannot be described as the independent product of qubits (5 qubits in the above diagram). So the end state cannot be described as the independent components of the qubits that make the whole state.
How an algorithm works in a quantum computer?
· At first, we prepare the computer to be in a super positioned state (1,2).
· Then we encode the problem by injecting the data into machine (3). The encoding happens through entanglement as discussed earlier, which is why we can observe a change in state.
· We have exploited the property of superposition and entanglement to encode the information, now with the principle of interference , we can combine the states and interfere them with one another to cancel things out and maximize the correct answer (4).
The complex entanglement described above can handle data better than the classical binary systems exponentially better. Below image shows a row by row comparison of qubits and classical bits.
This helps us solve problems that we couldn’t solve with classical bit systems , problems that have exponentially large number of variables or heavy-optimization tasks.
I will discuss about the application of Quantum computing in my next article.
