# Questions tagged [models]

For questions on theoretical models of quantum computations. Such models may be realistically 'build' in real machines, but not necessarily.

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### Are ladder operators ever extensively used in any model of quantum computation?

Computer scientists and others who are interested in learning more about quantum computation might be exposed, or re-exposed, to various concepts and classes of matrices from linear algebra. For ...
30 views

### Why does the condition $\langle \varphi _k\left( t \right) |\dot{\varphi}_l\left( t \right) \rangle =0$ called parallel transport condition?

I'm reading this paper about nonadiabatic holonomic quantum computation and met the condition eq.(2) states that $\langle \varphi _k\left( t \right) |\dot{\varphi}_l\left( t \right) \rangle =0$ is the ...
1 vote
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### How to simulate $H(\theta) = B(\sin\theta S_1^x +\cos\theta S_1^z +\sin\theta S_2^x +\cos\theta S_2^z)+aS_2^zI_z$ on IBM Qiskit

I am trying to simulate this Hamiltonian on IBM Qiskit, for varying values of $\theta$: $H(\theta) = B(\sin\theta S_1^x +\cos\theta S_1^z +\sin\theta S_2^x +\cos\theta S_2^z)+aS_2^zI_z$ Where S is ...
1 vote
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### What is the relation between the database made up of N elements and the index made up of a string length n in the query model?

I am working on a circuit model that contains a blackbox (query) and do not understand the relationship between what is in the black box and the way we get out the value of the element we index. The ...
123 views

### unexpected effect of coherent unitary error in qiskit

I'm trying to simulate the effect of a coherent unitary Z rotation at an arbitrary angle of a single qubit on the fidelity of a quantum circuit. I am using the qiskit Aer noisy simulator. More ...
50 views

### What type of tasks it is possible to solve on a quantum simulator?

In this article, the author claimed that researches from Harvard and MIT created 256 qubits quantum simulator. However, we are not talking about piece of software on a classical computer but actual ...
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### Where is entanglement present and absent in the one clean qubit model of computation?

Based on my limited and poor understanding, a quantum circuit in the "one clean qubit" model of quantum computation generally acts on a single pure (clean) qubit tensored with $n-1$ qubits ...
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1 vote
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### IBM Q Experience - Can it be used draw out ML inferences? [closed]

Are there Quantum-enhanced Machine Learning algorithms that can be implemented via Qiskit in IBM Q Experience and obtain valuable inferences faster than their classical counterparts from datasets of ...
1 vote
53 views

### Screening procedure in an iterative qubit coupled cluster (iQCC) ansatz

The paper Iterative Qubit Coupled Cluster approach with efficient screening of generators describes a new screening procedure for generators of the QCC ansatz. How does one get from defining the ...
1 vote
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### Can We Currently Import Quantum Datasets (Datasets Containing Quantum Data) Onto NISQ-era Quantum Computers?

I'm still investigating the TFQ whitepaper. In one section of the paper, the authors say this with respect to Quantum Datasets In general, [a quantum dataset] might come from a given black-box ...
1 vote
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### Application Query [closed]

I had written earlier to propose an econometric modeling application that may lend itself to a quantum computing approach, and was asking how best to proceed. The model would be centered around the ...
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### How to measure one of the qubits in a two-qubit register?

How do I measure the first qubit of an entangled vector, say \begin{pmatrix} 1 \\ -1 \\ 0 \\ 0 \\ \end{pmatrix} is what I get on the end of Deutsch's algorithm. If I get it right, I should now ...
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### How close are we in achieving computation over reals using quantum qubits? [duplicate]

I recently attended a seminar where a professor of quantum cryptography told the audience that one quantum qubit can theoretically store "infinite information". I was very intrigued by this statement, ...
334 views

### Is quantum parallel search impossible?

Scott Aaronson's blog notably states: Quantum computers would not solve hard search problems instantaneously by simply trying all the possible solutions at once. Is this a statement of a law, as ...
108 views

### Why do quantum computation models based on open quantum systems receive so little attention?

In almost all research on (universal) quantum computation the common models assumed from the outset are either the quantum circuit model with unitary gates, the measurement-based one-way model or the ...
112 views

### Why is the resource theory approach used in quantum information processing? [closed]

What are the advantages and applications of using the resource theory approach in QIP ? What specific problems can be solved using in particular this approach ?
1 vote
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### Is there an inherent difference in need for error correction between quantum annealing and gate based methods?

When I read about computing using gate based methods, I mainly read about the difficulties with error rates, circuit depth (and connectivity) and not enough qubits. With computing using quantum ...
128 views

### Aren't reversible logic gates a necessity for efficiently executing quantum algorithms?

The Wikipedia article on logical reversibility says: ...reversible logic gates offered practical improvements of bit-manipulation transforms in cryptography and computer graphics. But I guess ...
78 views

### Correspondence between the Topological model and Quantum Circuit model

For example, given the $R$ & $F$ gates and Toric codes for a given problem, how to convert this code into the conventional circuit model and vice versa. From the literature developed, it seems ... 172 views

### Quantum computing concepts

I am trying to develop a feel for quantum computing at a basic level. I would very much appreciate someone will take a look at the statement below and fix it, since I assume it needs fixing. “...
162 views

### What good references would you recommend to understand the (continuous-variable) CV model of computation?

If you have good references about the CV model that are understandable from a computer science background, that would be great. If they include numerical examples, that would even be better.
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### How does topological quantum computing differ from other models of quantum computing?

I've heard the term Topological Quantum Computer a few times now and know that it is equivalent to quantum computers using circuits with respect to some polynomial-time reduction. However, it is ...
112 views

### Which theoretical models for quantum computing are polynomial-time equivalent? [duplicate]

There are different theoretical models for quantum computing like the circuit model or the model of adiabatic quantum computers. Between which of these models exist polynomial-time reductions? Note ...
476 views

### Who built the first quantum computer using at least two qubits?

In my previous question I asked who invented a quantum computer using qubits. As a follow-up to this question I want to ask who built the first quantum computer using at least two qubits. During my ...