Next-generation D-Wave QPU

https://medium.com/d-wave/a-sneak-peek-into-our-next-generation-advantage-quantum-computer-3cbe8def208e

On June 10, 2022, D-Wave published a press release about next-generation QPU. Advantage2 will have more than 7000 qubits; the new topology is called the Zephyr topology, and the degree is 20. In other words, the new QPU is a specification that surpasses the current "Advantage," which has about 5000 qubits and 15 orders (Pegasus topology).

Already the demo version which has 500 qubits is released in D-Wave Leap. And that features are below.

Japanese Version →

1. More compact embeddings

A note on embedding: When performing quantum annealing on a real machine, an operation called minor-embedding is required. If the graph structure of the Hamiltonian you want to solve differs from that of the physical qubit graph, you cannot naively encode the problem into the device. For this reason, multiple qubits on the hardware are mapped to the same logical bits, as shown in the figure below. This mapping is called embedding, and the set of qubits corresponding to the same logical bit in hardware is called a chain.

Figure in [3]

• While embedding creates chains, too long chains degrade the quality of the solution, and the increased order of Advantage2 allows embedding with shorter chains, even for dense problem graphs.
• The documentation of D-Wave also mentions that the maximum chain length that can be expected to provide a stable solution is 5-7 qubits [3].
• D-Wave's visualization tool, dwave.inspector also alerts the user to the presence of chains longer than seven qubits.

2. Increased energy scale

Dr. Emile Hoskinson, Advantage2 development leader, says,

Increasing the energy scale increases the depth of the valleys; this makes them easier to find and makes it harder for noise to knock the system out of them. What we get is both an improved solution quality and an increased probability of finding good solutions, because we can cut through the system noise more easily [1].

For those unfamiliar with physics, the relationship between noise and energy scale, such as temperature, will be the subject of a future article.

3. Reduction of error rates

New devices have lower error rates than conventional devices due to the above two and other factors.

The demo version of Advantage2, which has about 500 qubits, is already available on Leap and can be touched by users.