A quantum computer is a type of computing device that utilizes phenomena related to quantum mechanics, such as superposition and quantum entanglement, to perform processing tasks. Unlike the traditional computers that employ binary digits, quantum computers use quantum bits, or qubits, that exist in a state of quantum superposition.
Quantum computers store and utilize data in the form of qubits that represent either of the two binary states, one and zero, or a superposition that includes both values and every value in between. This allows quantum computers to perform tasks at a much greater scale and speed as compared to traditional computers. Due to their enormous computational power, they pose a great problem to the areas of encryption and cryptography that depend on factoring very large numbers to protect sensitive data.
A quantum computer is capable of performing one million computations simultaneously, as opposed to one performed by a traditional digital computer, as of 2014. A quantum computer running at 30 qubits has the same processing power as a digital computer that runs at 10 teraflops. This means it run at trillions of floating-point operations in just one second, as opposed to a typical computer in 2014, which runs on billions of floating-point operations every second.
The entanglement aspect of quantum mechanics comes into play when trying to determine the state of a qubit without having it lose its superposition. In theory, two separate atoms can become entangled by applying an external force to them, which allows a quantum computer and the person operating it to determine the value of qubits without directly observing them. This avoids quantum decoherence and the collapse of a qubit into one of the two binary states.
Although the idea of a practical quantum computer still remains in the realm of theory as of 2014, researchers can create rudimentary systems that utilize quantum computing to solve simple problems.