Education

The first building block of a quantum computer

Delft researchers completed the first step in building a quantum computer, and their flux qubit has earned them an article in the scientific journal, Science.

When a thousand of these qubits are switched together, the Holy Grail is reached: the quantum computer .

Within fifteen years, quantum computers will be available in stores, claims Professor Hans Mooij of the TU’s Nanoscience department. That is, if researchers work hard in the coming years. Mooij’s researchers certainly are: in a few weeks Science will publish news of their groundbreaking invention: the first switch for a quantum computer.

This switch (qubit) is nothing more that a super conducting aluminum ring measuring two thousandths of a millimeter. In this ring are about milliard electrons that are capable of streaming to the left and right at the same time. This mechanism, in which a small particle assumes two conditions simultaneously, is called superposition.

In regular computers, the bit is the smallest switch that can be on or off, presenting either a 0 (zero) or a 1 (one). But in quantum computers, the ‘bits’ are concurrently a zero and a one. Because of this superposition character, a quantum particle has much more memory than regular computer bits. ,,This ability is great for disintegrating large numbers in factors,” Mooij says. ,,Like you disintegrate the number 15 into 3 and 5. This can be used to crack codes, like pin codes, but also for other large calculations.”

Delft researchers dropped microwave radiations on their qubit, arousing a vibration in such a way that the qubit assumed a precise described superposition. Precision is needed for quantum computers. To measure the superpositions of the electrons in a qubit, highly sensitive instruments are needed: squids (superconducting quantum interference devices).Squids measure magnetic fields. The squid is built around the aluminum ring and measures how the qubit assumes both its positions.

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One qubit doesn’t make a quantum computer. Mooij says the next step is two couple two qubits together. ,,We can already do that, but not yet satisfactorily. Every time we measure the first qubit, the other one is influenced. We don’t want that disturbance.” Mooij says that a thousand qubits together are needed for a quantum computer. ,,But a hundred qubits together are also interesting to make calculations with.” A thousand quibit quantum computer is smaller than a thumbnail.

According to Romanian Post-doc researcher Irinel Chiorescu, the success of future applications for classic ‘outside’ world applications is dependent on extracting correct information from the quantum computer. As long as the quantum information stays in the aluminum ring, the researchers can control the process. Errors occur when there’s contact with uncontrolled conditions in the external world. ,,We have a lot of work still to do on this,” says Chiorescu, adding that the Delft qubit is better than otherresearch group qubits, because the Delft qubit is less sensitive to disturbances and relatively easy to work with. However, there’s a lot more research to be done regarding the usability of the quantum bits. ,,It isn’t only a step towards the quantum computer, it also provides insight into fundamental physical questions. Only, it’s not for tomorrow.”

Delft researchers completed the first step in building a quantum computer, and their flux qubit has earned them an article in the scientific journal, Science. When a thousand of these qubits are switched together, the Holy Grail is reached: the quantum computer .

Within fifteen years, quantum computers will be available in stores, claims Professor Hans Mooij of the TU’s Nanoscience department. That is, if researchers work hard in the coming years. Mooij’s researchers certainly are: in a few weeks Science will publish news of their groundbreaking invention: the first switch for a quantum computer.

This switch (qubit) is nothing more that a super conducting aluminum ring measuring two thousandths of a millimeter. In this ring are about milliard electrons that are capable of streaming to the left and right at the same time. This mechanism, in which a small particle assumes two conditions simultaneously, is called superposition.

In regular computers, the bit is the smallest switch that can be on or off, presenting either a 0 (zero) or a 1 (one). But in quantum computers, the ‘bits’ are concurrently a zero and a one. Because of this superposition character, a quantum particle has much more memory than regular computer bits. ,,This ability is great for disintegrating large numbers in factors,” Mooij says. ,,Like you disintegrate the number 15 into 3 and 5. This can be used to crack codes, like pin codes, but also for other large calculations.”

Delft researchers dropped microwave radiations on their qubit, arousing a vibration in such a way that the qubit assumed a precise described superposition. Precision is needed for quantum computers. To measure the superpositions of the electrons in a qubit, highly sensitive instruments are needed: squids (superconducting quantum interference devices).Squids measure magnetic fields. The squid is built around the aluminum ring and measures how the qubit assumes both its positions.

Thumb

One qubit doesn’t make a quantum computer. Mooij says the next step is two couple two qubits together. ,,We can already do that, but not yet satisfactorily. Every time we measure the first qubit, the other one is influenced. We don’t want that disturbance.” Mooij says that a thousand qubits together are needed for a quantum computer. ,,But a hundred qubits together are also interesting to make calculations with.” A thousand quibit quantum computer is smaller than a thumbnail.

According to Romanian Post-doc researcher Irinel Chiorescu, the success of future applications for classic ‘outside’ world applications is dependent on extracting correct information from the quantum computer. As long as the quantum information stays in the aluminum ring, the researchers can control the process. Errors occur when there’s contact with uncontrolled conditions in the external world. ,,We have a lot of work still to do on this,” says Chiorescu, adding that the Delft qubit is better than otherresearch group qubits, because the Delft qubit is less sensitive to disturbances and relatively easy to work with. However, there’s a lot more research to be done regarding the usability of the quantum bits. ,,It isn’t only a step towards the quantum computer, it also provides insight into fundamental physical questions. Only, it’s not for tomorrow.”

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