The quantum computer is every IT specialist's hope and every average Joe's dream. It is essentially a computer that makes direct use of distinctively quantum mechanical phenomena for computation, like superposition and entanglement, to perform operations on data.

In a classical (or conventional) computer, the amount of data is measured by bits while in a quantum computer, the data is measured by qubits (Quantum bits). The basic principle of quantum computation is that the quantum properties of particles can be used to represent and structure data and that quantum mechanisms can be devised and built to perform operations with these data.

For the moment quantum computers are just a bunch of theories, some answers and solutions, but mostly questions and practical conundrums.

Finally, we may see some technological advances in this area, as NEC Corporation, Japan Science and Technology Agency (JST) and the Institute of Physical and Chemical Research (RIKEN) have announced the successful demonstration of the world's first quantum bit (qubit) circuit that can control the strength of coupling between qubits.

One of the problems in the design of a practical quantum computer is how to control the coupling strength between qubits. A few others are the states of the two qubits (logic operation) and the states of individual qubits.

The announcement regarded the successful development of key technologies for the world's first solid-state qubit and the world's first two-qubit logic gate, based on solid-state technology that excels in its ability to integrate qubits.

The next step for the research group was to address the controllable coupling of qubits to realize a practical quantum computer. Their new research result represents the world's first successful demonstration of controllably coupled qubits.

Innovation comes from using another qubit in between the two qubits for coupling. The coupling qubit functions as a non-linear transformer that is able to turn on and off the magnetic coupling between the two qubits, and on/off control is achieved simply by inputting a microwave. The important thing is that the coupling operation has been achieved without shortening the lifetime of each qubit. Scalability is also realized through the repetition of coupled two-qubit units, a feature necessary for future quantum computers applications.

The experiment presented the coupling of a two-qubit system, the smallest quantum logic unit, made to carry out a multi-quantum control operation involving the turning on and off of the coupling. The results were very encouraging, as a simple quantum protocol has been successfully demonstrated, allowing controllable coupling for the execution of quantum algorithms.