Advanced Control of a Six-Qubit Quantum Processor in Silicon

 Advances in silicon spin .....

Advanced Control of a Six-Qubit Quantum Processor in Silicon

By QuTech, October 7, 2022

The research shows that it's possible to increase the silicon spin qubit count while keeping the same precision as for single qubits.

Researchers at QuTech, a collaboration between the Delft University of Technology and TNO, the Netherlands Organization for Applied Scientific Research, have developed a chip with six silicon-based spin qubits that operates with a low-error rate. The research is seen as a stepping stone for the development of scalable silicon-based quantum computers.

The researchers created an array of six "quantum dots" made of individual electrons spaced 90 nanometers apart. They controlled and measured the spin of the individual electrons and facilitated their interaction using microwave radiation, magnetic fields, and electric potentials. The work is described in Nature.

"In this research we push the envelope of the number of qubits in silicon, and achieve high initialization fidelities, high readout fidelities, high single-qubit gate fidelities, and high two-qubit state fidelities," says Lieven Vandersypen, QuTech's director of research. "What really stands out though is that we demonstrate all these characteristics together in one single experiment on a record number of qubits."

From QuTech

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D-Wave 500 Qubit Quantum Machine on the Cloud

Recall out interaction with D-Wave now dome time ago. often mentioned here. Qubit count is now  impressive.    They continue to advance with their specialty machines.     Would like to see more examples of their applications now.

D-Wave's 500-Qubit Machine Hits the Cloud   By IEEE Spectrum,  July 14, 2022

When quantum-computing pioneer D-Wave releases its next-generation Advantage2 system in 2023 or 2024, the company expects its 7,000-qubit machine to be the most powerful quantum computer of its kind in the world. Now D-Wave is making an experimental prototype of Advantage2 immediately available for use over the cloud.

Classical computers switch transistors either on or off to symbolize data as ones or zeroes. In contrast, quantum computers use quantum bits, or "qubits." Because of the strange nature of quantum physics, qubits can exist in a state called superposition, in which they are essentially both 1 and 0 at the same time. This phenomenon lets each qubit perform two calculations at once. The more qubits are quantum mechanically linked, or entangled, within a quantum computer, the greater its computational power can grow, in an exponential fashion.

The standard approach toward building quantum computers, called the gate model, involves arranging qubits in circuits and making them interact with each other in a fixed sequence. In contrast, D-Wave—based in Burnaby, B.C, Canada—has long focused on what are called annealing quantum computers. Quantum cousins of classical annealing computers, these machines find a lowest energy state by slowly cooling it down—in much the same way that metals and crystals are sometimes tempered so as to minimize imperfections. Quantum annealing machines, then, start off with a set of qubits whose interactions at their lowest energy state, called the ground state, represent the correct answer for a specific problem the researchers programmed it to solve.

From IEEE Spectrum

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Qubit Supercharged: Researchers Introduce the Qutrit

New Quantum State proposed: The Qutrit.   Will this prevail?

The Qubit Supercharged: Researchers Introduce the Qutrit

By Tom's Hardware, January 6, 2022

Rigetti Computing has announced a new development in quantum computing, unlocking a third quantum state, called qutrits.  Qubits typically perform calculations across two possible quantum states, with their "ground state" corresponding to "0" and their "excited state" corresponding to "1."

Qutrits allow for increased performance by achieving a third state, corresponding to "2."   Qutrits hold more information than qubits, with encoding possibilities between 0 and 2, while qubits allow for encoding between 0 and 1, after which stability dramatically decreases.

Qutrits also can unlock new error-correction techniques.  Rigetti indicated qutrits can provide useful work only in a "many microseconds" scale.

The company's's qutrit systems have been made available on an experimental basis for researchers and clients via its Quil-T instruction-set architecture for quantum computing.

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Quantum Computing Error Correction

Error correction in context  is key.

Milestone in Quantum Computing With Error Correction

By SciTechDaily, December 20, 2021

Scientists at Dutch quantum computing research institute QuTech have integrated high-fidelity operations on encoded quantum data with a scalable framework for repeated data stabilization, a key milestone in the development of quantum error correction.

The resulting logical quantum bit (qubit) features seven physical qubits or superconducting transmons.

QuTech's Jorge Marques said, "We do three types of logical-qubit operations: initializing the logical qubit in any state, transforming it with gates, and measuring it. We show that all operations can be done directly on encoded information. For each type, we observe higher performance for fault-tolerant variants over non-fault-tolerant variants."

From SciTechDaily    View Full Article

Triple Qubit Entanglement

Enticing piece ... implications?   Had only heard of two bit entanglements.   examining. 

 Quantum Computing: Triple Qubit Entanglement Achieved in Research Breakthrough

By Francisco Pires 3 days ago

Another step on the road towards quantum scalability

Researchers with the Riken Center for Emergent Matter Science in Japan have demonstrated a triple-qubit, silicon-based quantum computing mechanism - opening up the road for increased scalability beyond a mere increment in total qubits on a given system. Previously, qubits had only been shown working in entangled pairs -- and this research demonstrates that entanglement (and thus computation) can actually be divided between three qubits.

Quantum computing rests atop qubits - the quantum equivalent of the modern transistor. But while typical transistors can only represent one value at any point in time (with that value being either zero or one), qubits benefit from the superposition mechanic of quantum physics, meaning that they can represent both states at the same time.   ... '