Physics combines many separate diamond quantum chips with photonic integrated circuit and manufactured with a 128-Kubany chip — the largest to date, a device of this type. In the future, such technologies may become the basis for the creation of multicomponent quantum computing systems. Work published in the journal Nature.
If the classical bit can be in only one of two mutually exclusive States (they are denoted by one and zero), the state of a qubit — a quantum bit that is slightly more complicated. It combines zero and one and is characterized by the probability of detection of a qubit in one of these States in the measurement. This feature of qubits theoretically gives a huge advantage in recording and processing information compared to conventional bits, but in practice, quantum computers have problems.
Quantum States can disintegrate, as the qubits to interact with each other, which limits the lifetime of the computing system and leads to errors. To the computer reliable to use, you need to put the time calculation in the time frame stable operation and to achieve acceptable low error rate requirements lead, in particular, to the necessity of increasing the number of qubits (according to various estimates, up to hundreds and even millions of units in the same computer). At the same time to increase their numbers is a difficult task, because in large systems difficult to maintain the stability of quantum States and to avoid the appearance of unequal qubits.
Researchers from the United States under the leadership of Noel WAN (Noel Wan) and Tsung-Ju Lu (Tsung-Ju Lu) from the Massachusetts Institute of technology used and explored one of the possible approaches to create quantum chip. In the role of qubits acted as artificial atoms — special defects of the crystal lattice of diamond, in which physics with focused ion beam built in germanium and silicon nodes. In their quantum properties of these defects is similar to conventional atom — they are the basic and excited energy levels, which correspond to the state of the qubit, and the transition between them is accomplished by the emission or absorption of photons of a certain frequency. However, compared to natural atoms, these systems are easier to control — they are located immediately inside the chip in a known fixed position.
Instead of having to connect all the qubits into a single diamond sample, the authors made a number of separate modules, and then selected the highest quality items and linked them by using photonic integrated circuits — systems aluminum-nitride (AlN) waveguides (exchange channels) on a sapphire substrate. Using micromanipulators , the scientists were able with the required accuracy to place the modules in the right places scheme, combining the diamond waveguides of the chip with aluminum-nitride waveguides on the platform.
As a result, researchers have produced a 128-channel combo chip of the sixteen eight-diamond modules — the largest at the moment, a device of this type, and, therefore, the experiments have shown promise (in the sense of increasing the number of qubits) modular approach to creating quantum chips. The authors emphasize that further research (which may already be devoted to the management of many qubits and their interactions), this method makes it possible to select and combine in one system the various materials on the basis of one or another of their properties.
Despite the fact that in General in its possibilities of quantum computers is inferior to conventional, they are already today find their application and compete with other computing devices. So, in may we talked about how 54-Kubany processor used for calculations in quantum chemistry, and most recently about how scientists have demonstrated the superiority of quantum computers in the math game.