laser computers

The clock frequency of 1 GHz in processors is one billion operations per second. A lot, but the best models currently available to the average consumer are already achieving several times more. What if it speeds up... a million times over?

This is what new computing technology promises, using pulses of laser light to switch between states "1" and "0". This follows from a simple calculation quadrillion times per second.

In experiments conducted in 2018 and described in the journal Nature, researchers fired pulsed infrared laser beams at honeycomb arrays of tungsten and selenium (1). This caused a zero and one state switching in the combined silicon chip, just like in a conventional computer processor, only a million times faster.

How did it happen? The scientists describe it graphically, showing that the electrons in the metal honeycombs behave "weirdly" (though not as much). Excited, these particles jump between different quantum states, named by experimenters "pseudo-spinning ».

The researchers compare this to treadmills built around molecules. They call these tracks "valleys" and describe the manipulation of these spinning states as "valleytronics » (S).

Electrons are excited by laser pulses. Depending on the polarity of the infrared pulses, they "occupy" one of two possible "valleys" around the atoms of the metal lattice. These two states immediately suggest the use of the phenomenon in zero-one computer logic.

The electron jumps are extremely fast, in femtosecond cycles. And here lies the secret of the incredible speed of laser-guided systems.

In addition, scientists argue that due to physical influences, these systems are in some sense in both states at the same time (superposition), which creates opportunities for The researchers emphasize that all this happens in room temperaturewhile most existing quantum computers require systems of qubits to be cooled to temperatures close to absolute zero.

“In the long term, we see a real possibility of creating quantum devices that perform operations faster than a single oscillation of a light wave,” the researcher said in a statement. Rupert Huber, professor of physics at the University of Regensburg, Germany.

However, scientists have not yet performed any real quantum operations in this way, so the idea of ​​a quantum computer operating at room temperature remains purely theoretical. The same applies to the normal computing power of this system. Only the work of oscillations was demonstrated and no real computational operations were performed.

Experiments similar to those described above have already been carried out. In 2017, a description of the study was published in Nature Photonics, including at the University of Michigan in the USA. There, pulses of laser light lasting 100 femtoseconds were passed through a semiconductor crystal, controlling the state of the electrons. As a rule, the phenomena occurring in the structure of the material were similar to those described earlier. These are the quantum consequences.

Light chips and perovskites

Do "quantum laser computers » he is treated differently. Last October, a US-Japanese-Australian research team demonstrated a lightweight computing system. Instead of qubits, the new approach uses the physical state of laser beams and custom crystals to convert the beams into a special type of light called "compressed light."

In order for the state of the cluster to demonstrate the potential of quantum computing, the laser must be measured in a certain way, and this is achieved using a quantum-entangled network of mirrors, beam emitters and optical fibers (2). This approach is presented on a small scale, which does not provide sufficiently high computational speeds. However, the scientists say the model is scalable, and larger structures could eventually achieve a quantum advantage over the quantum and binary models used.

2. Laser beams passing through a tangled network of mirrors

“While current quantum processors are impressive, it is unclear whether they can be scaled to very large sizes,” Science Today notes. Nicolas Menicucci, a contributing researcher at the Center for Quantum Computing and Communication Technology (CQC2T) at RMIT University in Melbourne, Australia. “Our approach starts with extreme scalability built into the chip from the very beginning because the processor, called the cluster state, is made of light.”

New types of lasers are also needed for ultrafast photonic systems (see also:). Scientists from the Far Eastern Federal University (FEFU) — together with Russian colleagues from ITMO University, as well as scientists from the University of Texas at Dallas and the Australian National University — reported in March 2019 in the journal ACS Nano that they had developed an efficient, fast and cheap way to produce perovskite lasers. Their advantage over other types is that they work more stably, which is of great importance for optical chips.

“Our halide laser printing technology provides a simple, economical, and highly controlled way to mass-produce a variety of perovskite lasers. It is important to note that geometry optimization in the laser printing process makes it possible for the first time to obtain stable single-mode perovskite microlasers (3). Such lasers are promising in the development of various optoelectronic and nanophotonic devices, sensors, etc.,” explained Aleksey Zhishchenko, a researcher at the FEFU center, in the publication.

3. Perovskite laser beams

Of course, we will not see personal computers “walking on lasers” soon. While the experiments described above are proofs of concept, not even prototypes of computing systems.

However, the speeds offered by light and laser beams are too tempting for researchers, and then engineers, to refuse this path.