Weizmann Institute of Science scientists present the first Israeli quantum computer; In its construction, innovative methods were applied that will help advance the field towards unprecedented computational capabilities
October 1955: "Weitzak", the first computer in Israel and one of the first in the world, was inaugurated at the Weizmann Institute of Science. 67 years later, a new chapter in the history of computing in Israel was recorded at the Weizmann Institute: in the laboratory of Prof. Roy Ozeri A universal quantum computer is developed - one of about 30 quantum computers in the world and less than 10 in ion trap technology. These days the researchers are working on the next project: a larger quantum computer that will be able to demonstrate a "quantum advantage" - the ability to perform calculations that ordinary computers, however powerful, cannot perform. These capabilities are the holy grail of the entire field, as they are expected to enable a multitude of applications in the future - from code cracking and financial forecasting, through a leap forward in artificial intelligence to the development of new drugs and materials. As a tribute to "Weizk" the next generation of the quantum computer will be called WeizQC.
Human progress in the last hundred years has relied on computers. However, our calculating machines, just like us, are bound by the laws of classical physics. This limitation constitutes a glass ceiling that does not allow a computational leap that will advance humanity on many fronts. Quantum computing machines, on the other hand, obey completely different laws - the laws of quantum theory that govern the world of microscopic particles. If in the world we know, a person, an object or a bit of a computer can necessarily be in one state, or in one place, quantum bits, affectionately called qubits, can be in more than one state at the same time. This jaw-dropping physical fact opens the door to tremendous computational power - infinitely greater than the most powerful computer in our world.
"Quantum computing is a technological-scientific promise that, until a few years ago, was limited to university research laboratories," says Prof. Ozari, who was one of the pioneers in the field in Israel when he returned 15 years ago from post-doctoral research in the USA under the guidance of Nobel laureate in physics David Weinland. "About seven or eight years ago, the promise broke through the boundaries of academia and a fast race to build a quantum computer began, with giants such as Google, Amazon and IBM at the forefront. At the same time, powers such as China, the United States and the European Union have also launched high-budget strategic plans to promote the field."
Despite the huge budgets and the mobilization of the most powerful bodies in the world, even today the road to a quantum computer with significant capabilities is still full of obstacles. One of the most prominent obstacles in the field is the great sensitivity of quantum computers to environmental noise, and the resulting difficulty in building large and complex computing systems. in the article published today in the scientific journal PRX Quantum The researchers, led by Dr. Tom Manovich and research student Yotam Shapira, present two innovations that face these challenges and were successfully implemented in the construction of the quantum computer in their laboratory.
Caution, trap
Unlike the computers we are familiar with that are all built with the same technology, in quantum computing there is currently a competition between different technologies for the first place. One of the prominent claims to the crown is the technology of ion traps, in which each ion - that is, an atom with an electric charge - constitutes a single qubit. Similar to bits that can switch between one state and another (0 or 1), ion-based qubits can also switch between different states represented by the orbit around the nucleus of the electron in the ion's outer shell. While in a normal computer the transition is through an electric current, in ion traps laser flashes are what move the qubits between their different states. These operations on the qubits are called logic gates. To perform complex calculations, operations must be performed on more than one qubit, but this is prone to disaster and may result in the loss of the quantum nature of the system. To this end, the researchers developed a pattern of using laser flashes that allows the creation of quantum logic gates that are more resistant to environmental noise. "The use of durable gates allows us to bring the computer we developed to a performance envelope similar to that which can be found today in the commercial world," says Prof. Ozari.
However, even when the logic gates are more durable, the high sensitivity of the system will eventually lead to an accumulation of errors and a rapid loss of the quantum advantage. Thus, an important pillar in the development of quantum computers is the non-trivial ability to perform error correction. To correct an error, one must first identify it, that is, measure the qubits, but measurement is an aggressive operation that will inevitably lead to the loss of the quantum character. The solution to this is to measure some of the qubits, but not all. In ion-based systems, the measurement of the qubits is done using optical systems: the ions are illuminated with a laser, and according to the scattering of the light (or lack thereof) they know how to differentiate between the different states of the qubits. In the computer developed at the institute, instead of the conventional light detectors that measure each ion separately and enable rapid processing of information, the scientists used a camera-based array that allows all qubits to be read at the same time. To maintain the quantum nature of the system, the researchers hid some of the qubits from the camera and overcame the slow data processing through the development of a fast system of electronic circuits that makes it possible to read the camera data, process the information and make decisions based on the measurement results.
The quantum computer we built in Prof. Ozari's lab currently includes five qubits - similar to the computers launched in IBM's cloud quantum computer services. The next generation of the computer being built these days is planned to include 64 qubits and is expected to enable the demonstration of a quantum advantage - an advantage that has been demonstrated so far in only two computers: in Google laboratories and in China.
Despite the status that Israel has gained in recent decades as a technological leader, even today many believe that in order to be a player in the international race for the quantum computer, the capabilities of an economic power are required - capabilities that apparently do not fit Israel's standards. Prof. Ozeri is outraged by this perception: "In Israel of the 50s, when there were camels and swamps here, they built one of the first computers in the world here. Today, Israel is a technological empire and there is no reason why we should not be at the forefront of the race for the quantum computer."
Dr. Tom Manovich, Yotam Shapira, Lior Gazit, Dr. Nitzan Akerman and other researchers and research students from the laboratory of Prof. Roi Ozari in the Department of Physics of Complex Systems participated in the construction of the quantum computer. The theoretical aspect of the project was led by Prof. Adi Stern from the Department of Condensed Matter Physics at the Institute.
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