A quantum Computer is any gadget for calculation that utilizes unmistakably quantum mechanical wonders. These computers are based on different science that is Quantum physics. These computers are also called future computers. Few companies like IBM, Google and Intel are producing and using this computer. Quantum computers are those computer with use bits or qubits for computation. Qubit or bit is the basic unit in of quantum information in Quantum computers.Normally we are using binary computers. In binary computers Processor use transistors for calculations. It can be in on-off statement. These computers use zero and one statement in the calculation.0 and 1 Statements are called “Bits”. But in quantum computers we use qubits. They have one extra function. In bits, information is exist in two state either it is 0 or 1, but in quantum bit case ,It can be exist in 0 state, 1state, or in both states. So it can increase the computation or calculation speed. When qubits is not observed, it can be in every possible state. This state is called “Spinning state”. It can be measured in up, down and both state.

#### Features of a Quantum computer

Quantum** **computers can solve those problems which are impossible to solve their more secure computers then any other computer a quantum computer can be hundred million times better than a classical computer and thousands of time faster than a conventional computer it can solveMultiple problems at the same time. Quantum computer describe the physics behaviour of fundamental particles like electrons and photons. So quantum computer boots by controlling the behaviour of these particles these computers are different from normal computer. It is based on different technology that is a quantum physics. They use much less energy than a supercomputer and in future they will compete with a supercomputer.

#### Drawbacks of a Quantum computer

Like each contraption it has likewise a few drawbacks . Quantum PCs are difficult to work. They are extremely hard to create in light of the fact that they change their state while watching. They make such a lot of noise. The fundamental drawback of processing is the innovation required to execute a quantum PC isn't accessible at present. The explanation behind this is the predictable electron is harmed when it is influenced by its condition and that electron is especially fundamental for the working of quantum PCs. They use a lot of power to work efficiently. It is dangerous for security purpose because they can be hacked easily.