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31 votes

Which subatomic particle does each company use in quantum computing?

Google, IBM and Rigetti use transmon qubits; these are basically fancy LC circuits where a Josephson junction and capacitor connect two superconducting islands. Because of this, they are also often ...
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  • 4,649
28 votes
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Is there proof that the D-wave (one) is a quantum computer and is effective?

There is still a search for problems where the D-Wave shows improvement over classical algorithms. One might recall media splashes where the D-Wave solved some instances $10^8$ times faster than a ...
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  • 1,679
27 votes
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How do you write a simple program for a D-Wave device?

The 'Hello World' equivalent in the D-Wave world is the 2D checkerboard example. In this example, you are given the following square graph with 4 nodes:        &...
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19 votes
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Why can't quantum annealing be described by a gate model?

A Quantum Annealer, such as a D-Wave machine is a physical representation of the Ising model and as such has a 'problem' Hamiltonian of the form $$H_P = \sum_{J=1}^nh_j\sigma_j^z + \sum_{i, j}J_{ij}\...
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  • 3,397
17 votes

Why can't quantum annealing be described by a gate model?

Annealing's more of an analog tactic. The gist is that you have some weird function that you want to optimize. So, you bounce around it. At first, the "temperature" is very high, such that the ...
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  • 1,457
11 votes

Is Google's 72 qubit device better than D-Wave's machines, which feature more than 2000 qubits?

There are two points I'd make here. D-Wave's computer and Google's computer are fundamentally different. D-Wave's computer is a quantum annealer. Imagine a landscape with some grassy hills. If you put ...
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  • 3,291
11 votes
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Is Google's 72 qubit device better than D-Wave's machines, which feature more than 2000 qubits?

Short explanation: D-Wave implements quantum annealing, while Google has digitized adiabatic quantum computation. Lengthy Explanation: D-Wave advertises their line of quantum computers as having ...
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  • 2,229
10 votes
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How much faster is “D-Wave Two” compared to its predecessor?

As Troyer and Lidar saw no speed increase with the D-Wave 1 compared to classical computers, the D-Wave 2 benchmark figure reported in 2013 of 3600 times as fast as CPLEX (the best algorithm on a ...
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9 votes

How do you write a simple program for a D-Wave device?

The title and question body seem to ask two different questions. In the title you ask "How do you write a simple program for a D-Wave device?", while in the question body you ask how to find the ...
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8 votes
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How to explain in layman’s terms the significance of the difference of qubits of the D-Wave and IBM QX?

In the classical case, there is a pretty big difference between digital computers and analogue ones. The methodology and hardware is very much distinct (in all cases I know of, at least). The divide ...
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8 votes

Is there proof that the D-wave (one) is a quantum computer and is effective?

Is there proof that the D-wave (one) is a quantum computer and is effective? D-Wave Video - Offers an explanation of: "How do we know ...": https://youtu.be/kq9VqR0ZGNc One analogy you might make ...
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  • 2,229
8 votes
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How are IBM's 127 qubits more potent than the 5760 qubits D-Wave - Advantage_system6.1?

They are different kinds of quantum computers: The D-Wave is a quantum Annealer. A rather specific (non-general purpose) device that can solve QUBO-type problems. IBM offers universal gate-based ...
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  • 455
7 votes

How much faster is “D-Wave Two” compared to its predecessor?

As far as I know the closest answer to your question for applications is given in the recent (still unpublished) work presented at the March meeting by Bibek Pokharel, where he compares graph 3-...
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7 votes
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Is it important for a quantum computer to be shielded by the magnetic field?

The DWave machine relies heavily on single-flux-quantum digital control for setting up qubit and coupler operating points, and for carrying out the annealing protocol. Any stray magnetic flux, if ...
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7 votes
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Why D-Wave 2000Q requires such a low pressure?

Pressure implies the presence of stray atoms flying around messing things up. The use of a vacuum is required to prevent this, as one of the ways of keeping the device well isolated from unwanted ...
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7 votes

How would D-Wave be used for complex optimization problems?

So I do not know much about yacht design but having played a little bit with a D-Wave machine I would suggest to see if you can model your problem as a Quadratic unconstrained binary optimization. See ...
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  • 4,554
7 votes

What are XX, YY, YZ etc. couplings?

In the mentioned context, what is meant is that, between a pair of qubits that are coupled, an XX coupling means something of the form $$ X\otimes X\equiv\left(\begin{array}{cccc} 0 & 0 & 0 &...
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6 votes

How do you write a simple program for a D-Wave device?

The inputs to the D-Wave are a list of interactions and more recently the annealing time of the qubits. As you mentioned the Ising problem is one of the easiest with $J_{ij} = 1$ in the problem ...
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  • 1,679
6 votes

How are IBM's 127 qubits more potent than the 5760 qubits D-Wave - Advantage_system6.1?

As the other answers have stated, they're two substantially different systems that are unfortunately both marketed as quantum computers. D-Wave is more specifically a quantum annealer. At a high level,...
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  • 186
5 votes

What is D-Wave's "Pegasus" architecture?

Pegasus is the first fundamental change in D-Wave's architecture since the D-Wave One. The D-Wave Two, 2X, and 2000Q all used the "Chimera" architecture, which consisted of unit cells of $K_{4,4}$ ...
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  • 11.9k
5 votes

Why D-Wave 2000Q requires such a low pressure?

The device works at cryogenic temperatures, which is so cold that all the gasses would freeze on the experiment device. Moreover, before they do so, they would conduct heat from the walls of the ...
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  • 201
5 votes
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What would be the simplest addition that would make the D-Wave architecture universal?

XX couplers are necessary to make an quantum annealing universal. https://arxiv.org/abs/0704.1287 As for fabricating them, I’m not too familiar with the hardware issues. Perhaps someone else can ...
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  • 1,679
5 votes
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When and where was the first use of the term Chimera?

The earliest non-internal reference I can find is in NIPS 2009 from a Google/D-Wave effort1. You'll notice that the two Choi papers, in addition to not using the term "Chimera", do not describe a ...
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5 votes
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What is the problem in demonstrating quantum supremacy?

D-Wave's 2000Q is a quantum annealer, not a circuit-based quantum computer like Google's Sycamore. The qubits in D-Wave's system are much noisier, less controlled and perform a fundamentally ...
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5 votes
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Moore's law for quantum computers

Moore's law deals with the number of transistors in an integrated circuit, which is used as a proxy for computational power. In a quantum computing device the analogy would be the number of qubits. ...
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4 votes
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What precisely is Reverse Annealing?

Until recently, D-Wave's quantum annealing devices always started from a uniform superposition over all $N$ qubits:               ...
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4 votes

Why did D-Wave choose the Chimera graph the way they did?

You are right that $K_{3,3}$ is non-planar, but as you said yourself, a larger $k$ is much better. If they could do $K_{1000,1000}$ that would be nice, because each qubit could be coupled to 1002 ...
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  • 11.9k
4 votes

Are there established best practices for designing Dwave embeddings?

On parameter setting, check our work: https://journals.aps.org/prx/abstract/10.1103/PhysRevX.5.031040 (Basically you want to make sure that the chains representing the logical qubit have a phase ...
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4 votes
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Are there established best practices for designing Dwave embeddings?

There are multiple factors that affect an embedding's performance, including what Davide mentions. Depending on your background, the following interpretation of Davide's answer might be easier for ...
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