A critical advance on the path leading to the construction of a quantum computer

Scientists at IBM reveal two significant innovations, which bring us closer to the actual realization of the quantum computer idea. For the first time, these researchers have demonstrated the ability to simultaneously detect and measure the two different types of quantum errors. At the same time, the researchers presented the design of a quantum chip circuit, which is the only architecture that can be successfully scaled to larger dimensions.

Scientists at IBM reveal two significant innovations, which bring us closer to the actual realization of the quantum computer idea. For the first time, these researchers have demonstrated the ability to simultaneously detect and measure the two different types of quantum errors. At the same time, the researchers presented the design of a quantum chip circuit, which is the only architecture that can be successfully scaled to larger dimensions.

As Moore's Law moves closer to the limit of possible miniaturization in the world of traditional silicon, quantum computing is expected to be one of the inventions that may herald a new era of innovation. Quantum computers open up new possibilities in the fields of optimization and simulation, which cannot be reached using the computers we know today. If it is possible to build a quantum computer that incorporates only 50 quantum bits (50 qbits) - this single computer will be stronger than any combined combination of the 500 most powerful supercomputers in the world operating today.

IBM's breakthrough is presented in the latest issue of the scientific journal Nature Communications, and for the first time presents the possibility of diagnosing and measuring the two different types of quantum errors (bit-flip and phase-flip), which will occur in a real quantum computer. Until today, it was possible to deal with only one of the two types in each measurement - however, the two were never measured at the same time. Such a measurement is an essential step in order to build a quantum error correction mechanism, which is a basic requirement in building a reliable quantum computer on a large scale.

The innovative and complex quantum circuit that IBM presented is based on a square lattice of four quantum bits with superconducting properties, located on a chip that is about a quarter of a square inch in size, and makes it possible to locate and measure quantum errors at the same time. The choice of a square structure, as opposed to a serial array that prevents simultaneous detection of the errors, presents the highest potential for expanding the scale of the quantum chip, by adding quantum bits until building a functioning quantum computing system.
If in the past traditional research in the field of quantum computing focused on applications in the fields of cryptography, today IBM believes in the ability of systems based on quantum particles to analyze and solve problems in the fields of physics and quantum chemistry, which cannot be solved today. These capabilities may have enormous potential in the fields of materials research or drug design, opening a gateway to a new world of applications.
Thus, for example, in the fields of physics and chemistry, quantum computing may allow scientists to design new materials or new medicines - without the need for expensive laboratory work conducted in a trial-and-error format, and thus carries with it the potential to significantly accelerate the pace of innovation in a long line of industrial fields.
In a world that handles huge amounts of Big Data, quantum computers will be able to quickly sort and curate larger databases than ever before, as well as huge volumes of unstructured information of various types. These capabilities may change the way humans make decisions, as well as the critical discovery processes in a variety of industrial research fields.

One of the biggest challenges facing scientists seeking to take advantage of the power inherent in quantum computing concerns controlling the inconsistency that characterizes the quantum phenomenon, and eliminating its effect on the computing system. This inconsistency is due to the formation of calculation errors, which are caused by the intersecting effect of factors such as heat, electromagnetic radiation and defects in materials. The errors are of particular significant interest in quantum machines, since the quantum information is particularly sensitive to any such error.

Previous works in this field, which were based on a linear array of quantum bits, were unable to simultaneously deal with the phenomena of bit reversal and state reversal. The results obtained in IBM's square quantum array move the researchers beyond this hurdle, thanks to the possibility of locating both types of quantum errors simultaneously for the first time, in a way that can be extended to larger systems as well.

to detect quantum errors
The most basic piece of information that a typical computer understands is a bit of information. Similar to light, which can be switched between on and off, a normal bit can have only two values: "0" or "1". However, a quantum chip is able to display each of these arrays - as well as both together, at the same time. The phenomenon, which has been named quantum superposition, is called simply "0+1". Marking this overlap is important, because the relationship between the states "0" and "1" actually forms the basis of the entire world of computing as it is known to us today. The overlapping mode will make it possible to significantly shorten the time required for processing and finding solutions to the problems presented to the computer, thanks to the possibility of reducing the number of processing movements required to perform each calculation.

Within the overlap mode, two types of errors may be detected: the first is a bit reversal, where "0" is replaced by "1" and vice versa. Here, it is a situation similar to the inversion of a chip known from the current world of computing, and previous works have already shown how to diagnose such a reversal occurring in a quantum chip. However, this is not enough to present a quantum error correction mechanism, because alongside the bit reversal, a state reversal may also occur: here, it is the reversal of the phase relationship between 0 and 1 in an overlapping state. Both types of errors must be detected simultaneously in order to allow the error correction mechanism to function properly.

The quantum information is particularly sensitive, because all the known technologies of quantum bits are exposed to the loss of information in every interaction with matter or electromagnetic radiation. Theoretical scientists have defined ways to preserve information for a significantly longer time, by means of dispersing the information between many quantum bits. "Surface Code" is a technique for a specific error correction method that spreads quantum information between a large number of quantum bits. The method allows only the nearest bit to encode one logical quantum bit, in a way that creates an array stable enough to operate without errors.

The IBM research team used a variety of techniques to measure the state of two independent quantum bit syndromes. Since these quantum bits can be designed and manufactured using standard silicon technologies, IBM anticipates that the moment it is possible to produce a handful of quantum bits in a reliable and serial manner, and to control these bits with a low error level, the basic barrier that prevents the operation of an error correction array in a large-scale quantum bit array will be removed. More.