Комментарии 14
Не знаете случайно, почему в кластере именно 8 кубитов? Кубик со стороной 2?
Нет, это планарный чип (делается традиционной литографией на собственном производстве).
Вот в 2007 был D-Wave Orion на 16 кубитов
http://www.dailytech.com/Worlds+First+Commercial+Quantum+Computer+Demonstrated/article6102.htm
Картинки из блога CTO D-Wave https://dwave.wordpress.com/ для ранних чипов (видна планарность, неясно где кольца):
https://dwave.wordpress.com/2007/01/19/quantum-computing-demo-announcement/
https://dwave.files.wordpress.com/2007/02/20070110_d-wave_orion_processor.JPG
Here is an optical picture of the processor we’ll be using for the demo. This particular circuit contains 16 qubits (the quasi-circular loops arranged in a 4×4 array). Each of the qubits is coupled to its nearest neighbors (N, S, E, W) and next-nearest neighbors (NW, NE, SW, SE) via a tunable flux transformer, giving a total of 42 of these couplers.
Виден чип https://dwave.files.wordpress.com/2007/02/sample-holder-with-europa-chip_small.JPG
5mK… a Leiden Cryogenics dilution fridge. These are beautiful, dependable machines that come highly recommended. We have three of these operational and haven’t had any problems with them in over 2 years of operation.
Используется литография http://arxiv.org/pdf/quant-ph/0403090.pdf
We also discuss how to implement this architecture specifically with superconducting persistent-current (PC) qubits [9, 10], which constitute a promising approach to lithographable solid-state qubits. We show that the proposed architecture is robust against manufacturing imprecision,
Кубитом является сверхпроводящая (ниобий) петля:
http://www.dwavesys.com/tutorials/background-reading-series/introduction-d-wave-quantum-hardware
http://www.dwavesys.com/sites/default/files/tut-hardware-qubit-loops.jpg
Figure 2. Left: A schematic illustration of 8 qubit loops (gold). The blue dots are the locations of the 16 coupling elements that allow the qubits to exchange information. Mathematically, these elements couple together variables in a problem that you wish the computer to solve.
По мотивам подробной публикации от D-wave мини обзор: http://nextbigfuture.com/2014/01/architecture-and-design-tradeoffs-of.html
Dwave has developed a quantum annealing processor, based on an array of tunably coupled rf-SQUID flux qubits, fabricated in a superconducting integrated circuit process. Implementing this type of processor at a scale of 512 qubits [Dwave now has a 1024 qubit processor in its labs] and 1472 programmable inter-qubit couplers and operating at ~ 20 mK… In particular Dwave reviews some of the design trade-offs at play in the floor-planning of the physical layout, driven by the desire to have an algorithmically useful set of inter-qubit couplers, and the simultaneous need to embed programmable control circuitry into the processor fabric.… The 512 single-stage, 3520 two-stage, and 512 three-stage flux-DACs are controlled with an XYZ addressing scheme requiring 56 wires.
И сама публикация с схемой:
http://arxiv.org/pdf/1401.5504v1.pdf Architectural considerations in the design of a superconducting quantum annealing processor; Fig 1 — Chimera unit cell topology
Layout sketch: qubit bodies are
represented by the elongated loops that span the whole width/height of the
unit tile. Each qubit is coupled to four others within the unit tile via the
internal coupler bodies (dark L-shaped objects). Qubits are coupled to others
in neighboring tiles via external couplers (lighter dashed rectangles). Control
circuitry (Φ-DACs and corresponding analog control structures) are placed
within light-shaded areas between the qubit/coupler bodies. (Right) Graph
representation: each unit tile corresponds to a complete bipartite graph K4,4
(dark nodes and solid line edges). Qubits from different tiles are coupled in
square grid fashion (dashed edges).
Слева — схема кубитов в блоке — 8 тонких сплющенных колец (4 горизонтальных и 4 вертикальных, если смотреть на чип сверху). Темные Г-образные элементы (internal couplers) управляемо соединяют кубиты в блоке (горизонтальные "x" с вертикальными "y"), светлые пунктирные прямоугольники (external couplers) соединяют одинаковые кубиты соседних блоков (с блоком вверх — x1 с x1;… x4 с x4; с блоком вправо — y1 с y1… y4 с y4 итд).
Вот так и получается "Граф Химера" из первых двух картинок поста (https://habrastorage.org/files/881/e23/137/881e231377264967afef97e103877065.png — слева в каждом блоке кубиты x1 — x4; справа y1-y4).
PS: в том же блоге доказательство — факторизация на квантовом компьютере никому не нужна и лишь делает мир хуже: https://dwave.wordpress.com/2007/02/24/factoring-as-a-red-herring/
So let’s say we lived in a world with factoring machines available at Walmart.… The reason is that when asked what QCs are good at, many QC experts respond with the factoring example, when there are several other perfectly great quantum algorithms that would also fit the bill. Why the focus on factoring? I’m not entirely sure, but here are two possible reasons:
- (1) how the algorithm works is technically very interesting (when people understand it, they usually say, man that’s cool!);
- (2) usually researchers are financed by the NSA, so it’s self-serving to put a line in the intro to your paper that lists code-breaking as an application, and then every paper written about QC starts with the same sentence, and the meme takes hold.
Why does it matter that experts focus on factoring? There are two reasons. The first is that factoring isn’t interesting from the applications/commercial perspective. It is hard to imagine how a company could become successful building machines that did nothing but factor products of primes. The second reason is that the application is very negative in the sense that it makes the world worse
In contrast to factoring, quantum simulation is both extremely commercially valuable (a large fraction of the world’s supercomputer cycles are currently spent solving the Schrodinger equation)
Успехи Google в квантовых вычислениях с точки зрения программирования