TU Delft progresses towards silicon quantum chip

Delft University of Technology scientists showed that quantum information can be transported via a Si photonic chip.

TU Delft researchers are advancing towards a silicon quantum chip that will bring quantum computers closer to commercial use. (Image credit: TU Delft)
TU Delft researchers are advancing towards a silicon quantum chip that will bring quantum computers closer to commercial use. (Image credit: TU Delft)

IMAGE: TU Delft researchers are advancing towards a silicon quantum chip that will bring quantum computers closer to commercial use. (Image credit: TU Delft)

The worldwide race to create more, better and reliable quantum processors is progressing fast, as a team of Delft University of Technology (TU Delft; Delft, Netherlands) scientists led by professor Vandersypen has realized yet again. In a neck-and-neck race with their competitors, they showed that quantum information of an electron spin can be transported to a photon, in a silicon quantum chip. This is important in order to connect quantum bits across the chip and allowing scaling up to large numbers of qubits. Their work was published in the journal Science.

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The quantum computer of the future will be able to carry out computations far beyond the capacity of today's computers. Quantum superpositions and entanglement of quantum bits (qubits) make it possible to perform parallel computations. Scientists and companies worldwide are engaged in creating increasingly better quantum chips with more and more quantum bits. QuTech in Delft is working hard on several types of quantum chips.

The core of the quantum chips is made of silicon. "This is a material that we are very familiar with," explains Professor Lieven Vandersypen of QuTech and the Kavli Institute of Nanoscience Delft, "Silicon is widely used in transistors and so can be found in all electronic devices." But silicon is also a very promising material for quantum technology. PhD candidate Guoji Zheng: "We can use electrical fields to capture single electrons in silicon for use as quantum bits (qubits). This is an attractive material as it ensures the information in the qubit can be stored for a long time."

Making useful computations requires large numbers of qubits and it is this upscaling to large numbers that is providing a challenge worldwide. "To use a lot of qubits at the same time, they need to be connected to each other; there needs to be good communication", explains researcher Nodar Samkharadze. At present the electrons that are captured as qubits in silicon can only make direct contact with their immediate neighbours. Nodar: "That makes it tricky to scale up to large numbers of qubits."

The core of the quantum chips is made of silicon. "This is a material that we are very familiar with," explains Professor Lieven Vandersypen of QuTech and the Kavli Institute of Nanoscience Delft, "Silicon is widely used in transistors and so can be found in all electronic devices." But silicon is also a very promising material for quantum technology. PhD candidate Guoji Zheng: "We can use electrical fields to capture single electrons in silicon for use as quantum bits (qubits). This is an attractive material as it ensures the information in the qubit can be stored for a long time."

Making useful computations requires large numbers of qubits and it is this upscaling to large numbers that is providing a challenge worldwide. "To use a lot of qubits at the same time, they need to be connected to each other; there needs to be good communication", explains researcher Nodar Samkharadze. At present the electrons that are captured as qubits in silicon can only make direct contact with their immediate neighbours. Nodar: "That makes it tricky to scale up to large numbers of qubits."

SOURCE: TU Delft; https://www.tudelft.nl/en/2018/tu-delft/quantum-race-accelerates-development-of-silicon-quantum-chip/

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