As part of the MIKOK project co-financed by the Polish National Centre for Research and Development (PLN 56 million), 'modular quantum computer infrastructure for special and military IT applications' is being developed in Warsaw. The consortium, led by the Warsaw University of Technology, also includes: the Military University of Technology, the Military Institute of Armament Technology, the Silesian University of Technology, and Sonovero R&D sp. z o.o.

The result of the project will be a prototype, i.e. not yet a production version, of a quantum computer infrastructure based on trapped calcium ions Ca(40)+. The infrastructure is scheduled to be launched by the end of 2025. Researchers are currently preparing both hardware and software to perform quantum operations. Most of the key components are being manufactured in Poland, including control electronics and quantum calculations optimisation software.

An important goal of building a quantum computer infrastructure from scratch by specialists in Warsaw is - as they say - to thoroughly understand the secrets of how such a system works, acquire unique practical skills and create the foundations for national technological sovereignty in this strategic area.

'We want to keep up with what is happening in the world, which is why we are taking the first key step', Zbigniew Wawrzyniak from the Warsaw University of Technology comments for PAP.

WHAT THE PROTOTYPE LOOKS LIKE

The first Polish quantum computer infrastructure is located in one room at CEZAMAT WUT. The device consists of an ion trap, precise lasers for cooling and changing the quantum states of trapped ions, electronic systems that control the lasers and the trap, and a management computer system with software for users.

The heart of the system is an ion trap braided with wires. Numerour devices around force the ions to 'work' and read the results. These include laser systems, fibre optics, measuring elements and optoelectronic systems, such as acousto-optic and electro-optic modulators. All these components must work simultaneously and precisely enough to perform operations on individual atoms.

'We have to trap the ions, cool them, set them appropriately with the electric field and force them to work by stimulating them with lasers', Wawrzyniak explains. And then the obtained quantum states, as the results of calculations, have to be recorded and interpreted.

This hardware infrastructure is to be a reliable foundation on which quantum algorithms can be performed.

'There are many different techniques for producing qubits. The advantage of calcium ions that we have chosen in our project is that they are +excellent+, because the energy levels of this isotope are well defined for the element itself, and their quantum states can be well controlled', Wawrzyniak says.

THE FACE OF QUANTUM COMPUTING

How will quantum computing work in Polish equipment? The hardest work is done by lasers with precisely selected wavelengths. First, calcium atoms are ablatively released from a pellet containing a piece of calcium with a pulse of laser light. Then, these released atoms are ionised and, thanks to laser cooling, they are trapped in a common trap, at a temperature close to absolute zero.

As a result of interaction with electromagnetic fields, the ions in the trap form a one-dimensional crystal that resembles beads in a necklace. In order to record information in these ions, these structures are excited with lasers. Under the influence of added energy, ions can transition from the base state to the so-called excited state.

Qubits, or quantum information units, are stored in stable quantum states of each ion. If an excited ion is illuminated with certain laser light, it will emit a photon, i.e. it will 'light up' (and an unexcited ion will not light up). This is how we know whether the excitation occurred as a result of previous operations or not.

WHAT OUR QUBITS CAN DO

While the state of an ordinary bit in a classical computer can be zero or one, the situation is more nuanced with qubits. The state of a qubit can be not only 1 or 0, but can be in a combination (superposition) of these states. Therefore, the entire 'sphere' of probabilities between states 0 and 1 is permissible. However, due to the nature of the states in qubits based on probabilities, it is necessary to perform the same calculation multiple times to obtain a statistically significant result.

In addition, individual ions can be quantum entangled with each other using lasers so that they jointly 'process' commands. Knowing how to use such non-obvious quantum properties provides completely new possibilities for calculations.

The Polish quantum computer infrastructure prototype is expected to ultimately reach 20 qubits. The quantum computer purchased in Poznań by PCSS (EuroQCS-Poland consortium) will have the same number. The compatibility results from the simple fact that both devices use ion trap technology.

If qubits could only do as much as ordinary bits, probably no one would invest millions in such solutions. A classic bit can be in one of the states 0 or 1. So if we have 20 bits, we have over a million different combinations of states (2 to the power of 20) to analyse. On the other hand, 20 qubits can represent all these states simultaneously and perform a given quantum algorithm for them.

The main advantage of quantum computers is that data are processed in a completely different way. Thanks to this, quantum computers can solve tasks that would take the largest conventional supercomputers many years.

GATEWAY TO PARADISE

In quantum computers, calculations are performed using quantum gates. The gate's task is to change the value of the qubit depending on the result of the task. In this case, however, the gate is not a physical object through which ions pass, but a system of ions with appropriate quantum states set by laser.

Quantum gates allow to perform a different type of operation than logical gates used in conventional computers.

The Polish team has already achieved a milestone in the project, creating the first chains of laser-cooled ions in this part of Europe as a key element in the construction of quantum gates. However, research installations are not yet about counting something that is uncountable and breaking the most advanced security measures, but about learning about the capabilities of new systems, because it is not known how progress in their operation can improve our lives (if we can make good use of them), or how much they can harm us (if they fall into the wrong hands).

To achieve quantum supremacy, i.e. to surpass the computational capabilities of conventional supercomputers with quantum computers, we still have a long way to go both in Poland and in the world..

Wawrzyniak explains that we still have a chance for quantum sovereignty and adapting solutions based on the latest scientific or technological discoveries. This will prepare a strong base of specialists in Poland who will be able to use this equipment and supervise its proper operation.

'We have to develop quantum techniques, because we have the potential to do it', he adds. 'We are able to improve a lot when it comes to this technology, because we have developed solutions that are at the world level. We also need to use this opportunity if we want to keep up with what is happening in the world', Wawrzyniak concludes.

MEASURABLE BENEFITS FROM CERN

'We have achieved high skills in designing superfast electronic systems and systems with nanosecond time precision. They are used in control systems in three quantum computer infrastructures in the world', Wawrzyniak says. He adds that Polish researchers gained this unique experience at CERN during the construction of the Large Hadron Collider. 'Electronics engineers supported experimental physicists there, creating control systems for experiments related to nuclear technologies. These are very similar, and often exactly the same systems', he explains.

Ludwika Tomala (PAP)

Science in Poland

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