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Questions tagged [d-wave]

A quantum computing company, based in Burnaby, British Columbia, Canada, mostly known for their quantum annealing computers. An early rendition of these, D-Wave One, was the first commercially available quantum computer. (Wikipedia)

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How to keep the initial Hamiltonian in D Wave

So the D wave machine claims to start in an eigenstate of the Pauli X term in the transverse Ising model Hamiltonian, $$ -\frac{A(s)}{2}\sum_{i} \sigma^{x}_{i} $$ and then $A(s)$ is turned off slowly ...
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Is there any quantum annealer simulator offered by DWave?

I am searching for quantum annealer simulator offered by DWave. I found classical solvers in dimod packages that implement simulated annealing, but I couldn’t find solver that simulates the real ...
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D-Wave Cloud Service - Pricing for Academic Research Project

In D-wave's web portal, I found 3 different ways that one can gain access to more QPU/Hybrid Solver time. One of them is the academic research project. Does anyone here have experience of carrying out ...
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Example Problem and/or Code for Quantum Annealing?

I have an interview with D-Wave tomorrow and want to make sure I'm prepared. Does anyone know of one or two in-depth, rigorous examples of quantum annealing that I could work through theoretically?
Ken Robbins's user avatar
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How to compare Quantum Annealing and Adiabatic Quantum Computing?

I'm still unsure on the difference between adiabatic quantum computing (AQC) and quantum annealing (QA). Please critique these interpretations: AQC: Define a Hamiltonian with an easy-to-prepare ...
Ken Robbins's user avatar
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Absolute value of a BQM: how to substitute it with constraint?

I need to build an expression for the objective to be minimized which is based on the L1-norm. For doing this, I need to take the absolute value of a BQM, which is not possible, at least at the moment ...
Roland's user avatar
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How to add constraints to a BQM?

BQM is unconstrained by definition. I need to submit a knapsack problem with two constraints (equality constraints + inequality constraints) to a quantum annealer (DWaveSampler). How would you set the ...
Roland's user avatar
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How to convert equality/inequality constraint to a BQM?

I need to submit a BQM to DWaveSampler. Since my problem has both objective and constraints, my understanding is that I need to add the latter as bqm to a composite BQM, which is then sent to the ...
Roland's user avatar
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Why does method to_bqm not maintain variables order?

When converting to bqm with .compile().to_bqm(), the original order of the variables is not maintained. To reproduce: ...
Roland's user avatar
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What arguments point towards D-Wave devices being potentially useful?

I'm looking for any evidence pointing towards D-Wave's approach to quantum computation being promising to achieve any sort of computational advantage with respect to classical devices. Note that I'm ...
glS's user avatar
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qiskit vs dimod: ising matrix in 2 libaries are different

I have a simple QUBO problem in qiskit library: ...
voxter's user avatar
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How to declare non-binary decision variables in an optimization problem?

I am working on a logistics problem which require me to find the optimum quantity of product to be manufactured and also to be shipped to satisfy the customer demand. I have made a decision variable $...
Another Random Guy's user avatar
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How can a QUBO matrix with many identical, non-zero off-diagonal terms be made sparse?

I am with a QUBO matrix where entire off-diagonal sections are with the same value, which is the same between sections. Consider the following example (much smaller than those I am actually working ...
T. Zaborniak's user avatar
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Can D-Wave machines be applied to simulate Hamiltonians arising in quantum physics?

AFAIK D-Wave primarily advertises their machines as tools for solving problems with classical input, i.e. when the Hamiltonian to be minimized is a function of $Z$s. Can one use their machines in ...
mavzolej's user avatar
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Why is quantum annealing often associated with the Ising model?

Quantum annealing is often associated with Ising Model, in the sense that the problem Hamiltonian needs to be in the form of an Ising Hamiltonian. Is this because the physical description of the ...
usercs's user avatar
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Is there any rigorous proof that Quantum Annealing provides a quantum advantage?

Is there any rigorous proof that Quantum Annealing (QA) is of any benefit (e.g. in terms of time to optimal solution, convergence rate, etc.) for a specific problem? Or any empirical evidence for the ...
Nepomuk Hirsch's user avatar
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How are IBM's 127 qubits more potent than the 5760 qubits D-Wave - Advantage_system6.1?

Hi I'm a newbie in quantum computing recently I had a look at the AWS braket and I've seen they had a machine called D-Wave - Advantage_system6.1 that has 5760 qubits but when I googled the highest ...
Zakaria Halloumi's user avatar
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Convert Hamiltonian to Ising Formulation or QUBO

I have a tridiagonal Hamiltonian matrix that I need to convert to QUBO or Ising format to use D-Wave's quantum annealing solvers. For a generic tridiagonal: \begin{pmatrix} a_1 & b_1 \\ c_1 & ...
Mudi Yang's user avatar
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Why do Quantum Annealer have (currently) a higher scaling potential?

One may categorize quantum computers in two classes: Quantum Annealer and (universal) Gate Quantum Computers. There may be also other categories. IBM announced 127 Qubits for their next Gate Quantum ...
choc1709's user avatar
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Penalty formulation regarding inequalitties

During the formulation of a QUBO matrix I have a question regarding penalty formulation. Once I'm done with QUBO formulation such as $x_{i}Ax_{j}$ where A is the QUBO matrix, $x_{i}$ and $x_{j}$ are ...
Kai-Chun Lin's user avatar
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Qubit fidelity of DWAVE device

Since DWAVE quantum device is constructed using superconducting flux qubits, each qubit cannot be produced identically so that the fidelity of the qubit must be different. DWAVE only provides the ...
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Is D-Wave advantage a noisier hardware compared to the older D-Wave 2000?

Is D-Wave Advantage noisier hardware compared to the older D-Wave 2000? There is any measure of the noise within the vendor's whitepapers, the quantum annealer analogue of e.g. decoherence time, ...
incud's user avatar
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Can D-Wave machines solve QUBO problems more efficiently than gate model devices?

I'm new to quantum annealing and D-Wave computer. I saw that it has about 5000 qubits which can solve a QUBO problem with 5000 variables. From my understanding, if we use a gate model device, say, an ...
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How do we calculate the offset in a QUBO formulation?

I am aware that for a quadratic optimization problem, we are required to minimize $y$ where $y = x^t Q x$ where $x$ is a column vector of binary variables and $Q$ is a QUBO matrix. I have the ...
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What is the role of Josephson junctions and biases in the D-Wave qubit structure?

On the D-Wave 2000Q there are up to 2048 qubits and 5600 coupler. A commonly used picture of one of such qubits is attached below. Each qubit is realized by a loop of niobium controlled by Josephson ...
Felix's user avatar
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What should be the lowest energy of this graph isomorphism QUBO?

I am trying to study QUBO formulations of the graph isomorphism problem. I tried implementing the QUBO matrices given by the algorithms described in here. For the two input graphs therein, I am ...
evil_potato's user avatar
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Sampling from a given Boltzmann distribution using D-Wave systems

For a project I'm working on, I want to use D-Wave systems to estimate the probabilities of a Boltzmann distribution given a QUBO (Hamiltonian), this being performed through sampling and the use of ...
THP202173582084's user avatar
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From general Hamiltonian to Ising Hamiltonian

I would like to convert my qubit hamiltonian fom the HeH+ system that I have obtained using Qiskit to an Ising or QUBO model. I have seen multiples examples from QUBO to Qubit Hamiltonian but on the ...
bjail66's user avatar
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How is eigendecomposition of a Hamiltonian equivalent to finding the minimum of an energy function?

This question is in regards to Dwave's quantum computer which is tailored to solve QUBO problems using quantum annealing. QM tells us that the ground state of a quantum system is given by the ...
morpheus's user avatar
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The Adiabatic Theorem - How to derive Schrödinger equation in the "s" variable

I'm studying Adiabatic Quantum computing from the book "Adiabatic Quantum Computation and Quantum Annealing: Theory and Practice" by Catherine C. McGeoch at D-Wave. The section THE ...
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Output of D-Wave LeapHybrid solver takes long to evaluate

we made the strange observation that the evaluation of the output in form of the dimod.SampleSet takes a long time to evaluate especially in comparison to the actual sampling step. Here is a minimal ...
Simon's user avatar
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How to improve embedding process in D-Wave?

I am quite new to the quantum computing field. Currently, I am trying to solve a combinatorial optimization problem on a D-Wave system, which I successfully translated into QUBO form. I also managed ...
Giovanni Iacovelli's user avatar
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1 answer
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What do the numbers in the Ising sampleset mean?

I am trying to create a portfolio optimization with the DWave Quantum Computer. I wrote some code trying to somehow reconstruct the following Ising model paper: Ai ...
Liza Darwesh's user avatar
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What is the state-of-the-art annealing device for solving Ising problems?

I understand that in addition to D-Wave's quantum annealer, there have been other unconventional (although non-quantum) Ising solvers like the one from Toshiba, Fujitsu, the Coherent Ising machine, ...
Arun's user avatar
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How to decide bias in Hamiltonian Ising model?

I am trying to code finance portfolio optimisation problem into a quantum annealer, using the Hamiltonian Ising model. I am using the dwave module ...
Liza Darwesh's user avatar
4 votes
2 answers
136 views

Why is it so important to have uniform chain lengths in a minor embedding?

Very brief background In quantum annealing, the discrete optimization problem we wish to solve (such as finding the minimum of $b_1b_2 - 3b_1 + 5b_3b_4$ for binary variables $b_i$) may have a ...
user1271772's user avatar
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From Qiskit QuadraticProgram to problem model accepted by d'wave ocean

Is there a way to convert QuadraticProgram (qiskit.optimization.problems.QuadraticProgram) to BQM used in D'wave ocean (e.g. <...
Alexei Osinovsky's user avatar
9 votes
3 answers
533 views

What is the computational complexity of quantum annealing?

Quantum annealing can be thought of as a black box solver that can find approximate solutions to hard optimization problems. For example, D-Wave quantum annealers can approximately solve quadratic ...
Dr. Prasanna Date's user avatar
9 votes
1 answer
474 views

Inequality constraints on D-Wave (using PyQUBO)

Inequalities cannot be directly converted into a QUBO form. By inequality, I mean something like this: 0⩽ Expression ⩽ N. We can introduce a slack variable and convert it to an equality problem: ⟹ ...
amp's user avatar
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D-WAVE QUBO Matrix Form

I am trying to write down this problem (friend/enemy graph) in a polynomial matrix form in order to understand quantum annealing better, but it seems like the problem should actually be split into ...
pars3c's user avatar
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What is the query complexity of the QUBO algorithm?

What is the complexity of the quantum unconstrained binary optimization (QUBO) algorithm in the number of queries to the quantum processor? To clarify, I'm asking about the complexity on quantum ...
Shen Zhuoran's user avatar
3 votes
2 answers
110 views

The commutation relation $[H_d, \sum_{i = 1}^n \sigma_i^z] = 0$ from the paper about the constrained quantum annealing (CQA)

A quote from the paper "Quantum annealing for constrained optimization" by I. Hen, F. M. Spedalieri: Let us now consider the driver Hamiltonian $$H_d = - \sum_{i=1}^n \left( \sigma_i^x \...
Davit Khachatryan's user avatar
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359 views

Moore's law for quantum computers

Moore's law states that performance of classical computers doubles every two years (later revised to 18 months) and a price for computing resources halves during same time period. Currently, it seems ...
Martin Vesely's user avatar
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1 answer
179 views

How do IBM, D-Wave, etc. change phase physically?

How do IBM, D-Wave, etc. change phase physically? In real hardware?
guest's user avatar
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2 answers
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What is an example of a simple QUBO problem?

I am digging into to the workings of the D-wave quantum annealing computers using this documentation. I find it very intuitive and well-explained, but their example of a "simple QUBO problem"...
Thomas Wagenaar's user avatar
9 votes
3 answers
233 views

Is there quantum advantage to be had with a D-Wave computer in 2020?

I've seen a lot of excitement in the popular press about the computers made by D-Wave Systems, but when I dig deep the only practical things that I can figure out that one can do with the computer are ...
vy32's user avatar
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How qubit phase is build in real hardware?

How qubit phase is build in real hardware? On IBM Quantum, D-Wave, etc?
guest's user avatar
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1 answer
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Quantum Annealing - Random results on big N

I implemented a solver for the Job Shop Problem, based on quantum annealing, on a D-Wave machine. I have a problem, that even though minimal energy solutions exist, they are only chosen once. I set ...
Robinbux's user avatar
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Is it possible to use D-Wave systems for free?

IBM offers its platform IBM Q for free with certain constraints, such as available quantum processors and number of jobs running in parallel. I was wondering whether there is the same possibility on ...
Martin Vesely's user avatar
18 votes
1 answer
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Which subatomic particle does each company use in quantum computing?

Probably each company (Google, Amazon, Intel, IBM, Microsoft, D-Wave and so on) uses a mix of subatomic particles and technologies. I would like to know which particles/technologies are used by each ...
Felipe Rojo Amadeo's user avatar