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Questions tagged [architecture]

For questions related to building of quantum computers and discussion of the hardware aspects.

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How can I get the structure of the variational ansatz for VQLS?

I have got a system of linear equations $$ A|x \rangle = |b\rangle \\ A = 0.45Z_3 + 0.55I \\ |b\rangle = H_1 H_2 H_3 $$ and I would like to solve it for $|x\rangle$. I am currently trying to ...
Matěj Šicner's user avatar
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46 views

If the main challenges limiting quantum computing's abilities will be passed, will even video games be run on quantum computers?

I'm terribly sorry for my lack of knowledge in (quantum) computer architecture, I still need to learn a lot. But I'd like to know whether quantum computers can execute the same tasks (like running a ...
me9hanics's user avatar
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7 votes
1 answer
310 views

Are indistinguishable bosons and fermions computationally equivalent to distinguishable qubits?

From the middle-late decades of the last century, many researchers such as Bennett, Benoif, Deutsch, Feynman, Manin, Wiesner, among others, had some intuition that qubits are computationally more ...
Mark Spinelli's user avatar
4 votes
3 answers
777 views

Are there qudit systems, and why are they not as popular as qubit systems?

Qudit is a $d$-level system that generalizes a qubit. From what I understood qudits are more resource efficient when it comes to spanning the state space. If $N$ is a dimension of a state space, then ...
MonteNero's user avatar
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The world's first quantum integrated circuit at the atomic scale - How does this advance quantum computing as a whole?

I have a hobbyist/enthusiast understanding of Quantum Computing, having read a few books on the subject. I came across this new article and referenced Nature paper. I know a goal of quantum computing ...
user2521987's user avatar
1 vote
1 answer
203 views

Gate times for photonic quantum computers

I am trying to understand the landscape of one- and two-qubit gate times for various quantum computing architectures. It is not so hard to find gate times for various gates such as Hadamard, CNOT and ...
Marion's user avatar
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Are there any quantum standards already in development and accessible as draft documents?

Are there any quantum standards already in development and accessible as draft documents? Any documents describing standardized way of describing and ensuring common meaning/interoperability, like e.g....
Mariusz's user avatar
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1 answer
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Good review articles on microwave hardware for superconducting qubit quantum computing?

I am trying to find some review articles on the microwave hardware used in superconducting qubit quantum computing. So far, most papers that I found seem to be high level overviews, e.g., Multilayer ...
LearnerAL's user avatar
2 votes
1 answer
57 views

Questions on Definitions and Concepts Regarding Toric Codes

Currently, I reading the toric code section in the beginning of the paper Topological Quantum Memory. Here are a couple of sections that are somewhat confusing to me. (1) This quote below is under a ...
Debbie's user avatar
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3 votes
1 answer
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A Particular Way of Erasing Ancilla Qubits

I am currently reading the paper Topological Quantum Memory by Dennis, Kitaev et. al. My main interest is to conceptually understand the idealized assumptions / requirements of a quantum computer ...
Debbie's user avatar
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What constitutes a quantum database?

Newb question, I know it's broad. I'm coming here for validated pointers, so I can know what to read. I have QT for CS (Yanofsky, Mannucci) and am reading about Shannon and Von Neumann entropy, but I'...
DukeZhou's user avatar
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1 answer
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What are the pros and cons of the most popular QC architectures?

I notice numerous companies and research groups around the world trying to build QC's with wildly different approaches. Intuitively, this suggests to me that QC is still very early in its maturation - ...
Andrew's user avatar
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0 answers
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Usefulness of having a cryogenic controller at 4K for transmons/spin qubits

There have been plenty of papers on the design of cryogenic control chips working at ~4K for qubit control and readout. These papers talk about how running coaxial cables from room temperature control ...
control freak's user avatar
5 votes
1 answer
161 views

Can we calculate the quantum volume of a classical computer?

The quantum volume is typically taken as a popular metric to determine the capability of a quantum computer to solve complex problems. Since the end goal is to develop quantum computers that can solve ...
Solarflare0's user avatar
2 votes
0 answers
21 views

Are classical analogues of quantum computers using superposed waves possible? [duplicate]

The trick of quantum computing is to take the advantage of wave mechanics (superposition) and entanglement. This allows to perform parallel computations/manipulations with $2^n$ superposed waves for $...
Sextus Empiricus's user avatar
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1 answer
89 views

Is there any quantum gate that can change quantum hardware topology(architecture)?

I read about this paper Hardware-aware Heuristic for the Qubit Mapping problem in the NISQ Era. I wonder there is the only SWAP gate that can change the quantum hardware topology. Is there any gates ...
김동민's user avatar
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Solution for the "Input and Output theory" for circuit/cavity-QED Quantum Architecture [closed]

This question consists of the basic calculations which are often referred to as "trivial" in most references in circuit-QED. However, are not so trivial for anyone who starts fresh into the ...
Siddhant Singh's user avatar
1 vote
0 answers
39 views

A distributed, scale-out quantum computing architecture?

Having been part of the mainframe, client-server, and now containers scale out architecture, I can observe the parallel and resemblance of today's quantum computers (massive) to that of the mainframe ...
Nathan Aw's user avatar
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9 votes
2 answers
337 views

Is there a good reason to use T-count minimization for circuits executed on current IBM open quantum systems (real hardware)?

As far as I understood from a series of papers, minimizing the T-count in Clifford+T circuits is essential for fault-tolerant ...
Psanfi's user avatar
  • 306
2 votes
1 answer
108 views

What determines the topology/connectedness of quantum computers?

Some quantum computers hold their qubits in a 2D array. I've even seen a 1D topology I think. On IBM Q, you can see which qubits talk to which qubit. I would like to know what determines/limits the ...
JoJo258OrAmI's user avatar
4 votes
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62 views

What is the executable opcode for Qiskit quantum hardware, as the quantum circuits or the transpiled/compiled QObj/ QASMQObj are assembly languages? [duplicate]

When we write a QASM code or build quantum circuit on Qiskit GUI, it converts it into QObj/QASMQObj (refering paper Qiskit Backend Specifications for OpenQASM and OpenPulse Experiments) or its ...
Shampa Sarkar's user avatar
2 votes
0 answers
28 views

What are the practical limitations of complementing quantum computations with memristors?

Considering the current state of research into quantum memristors, and the advantages/disadvantages of quantum and memristor driven computing architectures: Quantum Memristors Quantum Memristor ...
bey's user avatar
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5 votes
6 answers
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How to build a quantum computer in your house?

As still quarantine is going on for some of us. I was wondering how to make a Quantum Computer in your garage. What may be the total cost for building one? Was inspired by this youtube video.
user57048's user avatar
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3 answers
451 views

Why don't quantum computing scientists build two 50-qubit processors and connect them in parallel instead of building one 100-qubit processor?

Isn't it more scalable to build multiple processors of a lower qubit and connect them in parallel instead of building one processor of a higher qubit?
sean's user avatar
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3 votes
1 answer
159 views

Is quantum computing the most advanced computing technology we will ever have? [closed]

Is there already evidence today (e.g. basic theoretical research or even prototypes) on what the next technolgy will be/could be that is superior to quantum computers? Or have we reached the "...
Johannes Walter's user avatar
2 votes
1 answer
88 views

Are all the IBM QX mapping bidirectional?

The connection between physical qubits of IBM devices are all bidirectional or there are some architectures that there existing some unidirectional connection? I found that in IBM Quantum experience, ...
peachnuts's user avatar
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6 votes
1 answer
1k views

What is the state of the art on Quantum Random Access Memories? [duplicate]

I realized that Quantum Random Access Memory (qRAM) was proposed to make quantum computers more similar to classical one. Currently quantum computers have very constrained memory, given only quantum ...
Martin Vesely's user avatar
3 votes
2 answers
188 views

Why IBM devices have the same number of qubit and the same architecture, but the error rates are different?

Here are two different IBM quantum online devices, Both of them have the 5 qubits and the same architectures. But why do they have different error rate? What's the different between them?
peachnuts's user avatar
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1 vote
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66 views

What are the general hardware components of a universal quantum gate computer?

Although the architecture of a quantum computer depends on the implemented qubit system, I still wonder what the general structure of hardware parts would be. Evidently, a quantum computer isn't ...
Jelle 3.0's user avatar
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How many types of quantum computers are currently being researched? [duplicate]

I came across a "new" type of quantum computer - photonic quantum computing. Is this type of technology of interest here? You may read about an example here. I wonder how many types of quantum ...
Moti's user avatar
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2 votes
1 answer
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Mightn't the cost of a quantum computer be lowered by building it on earth sans cooler and then using it in the frigid vacuum of space?

I'm picturing the control equipment on the inside of an ISS wall with the part that needs being cold being on the outer side. I imagine this has been considered and if so, was the idea rejected for ...
Ruminator's user avatar
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4 votes
1 answer
1k views

Why are superconducting qubits the most popular approach to build a quantum computer?

There are many different physical implementations of qubits: NMR, spin qubit, N color center in diamond, superconducting qubit, trapped ions, photonics quantum computing, topological qubit, etc. ...
Junye Huang's user avatar
4 votes
1 answer
154 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 ...
quantumorsch's user avatar
5 votes
2 answers
245 views

Location of "bad" qubits on Sycamore

The Sycamore paper from Google notes that Sycamore is a $54$-qubit quantum processor, but for their experiments only $53$ qubits were working. The "bad" qubit was on the edge of the array. Is ...
Mark Spinelli's user avatar
5 votes
1 answer
402 views

What are the physical reasons behind noise/errors in quantum computers?

We know that the current quantum computers are noisy/error-prone. They are susceptible to gate errors (single qubit and multi-qubit), decoherence (relaxation and dephasing), readout error, etc. I want ...
Edifice's user avatar
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8 votes
2 answers
616 views

What design considerations set the frequency bounds for superconducting qubits?

Superconducting qubits generally have frequencies within the range of 4 - 8 GHz. What design considerations give the upper and lower bounds for what is a feasible design. I.e, why can't they be higher ...
psitae's user avatar
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6 votes
1 answer
602 views

Physical qubit of optical quantum computer

I was researching how optical quantum computers work and discovered a KLM protocol that allows for building quantum gates using linear optics elements like mirrors, beam splitters, and phase shifters. ...
Aleksandar Kostovic's user avatar
5 votes
1 answer
139 views

IBM Q devices' hardware/resource constraints

I tried to look for the resource constraints but so far haven't been able to find them. They are not present in the GitHub repository that usually provides the hardware information for the different ...
Kelthar's user avatar
  • 149
4 votes
1 answer
1k views

How is a physical qubit measured and how is the result interpreted?

To my understanding, most of the qubits we use today are just Josephson junctions coupled to a resonator that is triggering the qubits to go to different states by using microwave pulses. The same ...
Aleksandar Kostovic's user avatar
9 votes
1 answer
406 views

Current limits on Grover search space

I was wondering why till date Grover search has been implemented only till 3 qubits (corresponding to size of database = 8). Refer this paper The reason why I ask is that we have much larger sized ...
Maharshi Ray's user avatar
3 votes
0 answers
51 views

Spin precession using a laser

According to Christopher Monroe: "Modular Ion Trap Quantum Networks: Going Big", the hyperfine states of the valence electron in the Yb+ is used as a qubit. I know that we can change the spin ...
Tech Solver's user avatar
2 votes
1 answer
110 views

What is the "TRIAD" graph and where can I find more information about it?

I was looking up how to program for a D-Wave machine and I came across this image which says it's the "optimal hardware graph" for a D-Wave machine: Unfortunately the image seems to have come from ...
user avatar
8 votes
2 answers
977 views

Understanding (theoretical) computing power of quantum computers

I am very new to quantum computing and just try to understand things from a computer scientist's perspective. In terms of computational power, what I have understood, 100 ideal qubits ... can ...
J. Doe's user avatar
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5 votes
1 answer
252 views

When and where was the first use of the term Chimera?

This is along the same lines as the earlier question: When was the first use of the word Entanglement? I was surprised to discover that when searching for "chimera" in both of Vicky Choi's minor-...
user1271772 No more free time's user avatar
2 votes
2 answers
178 views

Can quantum computers be clustered together?

I have been interested in the idea of computer clusting which is about making multiple pysical computer system to act as one whole logical computer system computing the same task at the same time, but ...
Henry WH Hack v3.0's user avatar
11 votes
1 answer
436 views

Does the D-Wave 2000Q satisfy DiVincenzo's criteria?

DiVincenzo's criteria for quantum computation are the following: A scalable physical system with well characterized qubits. The ability to initialize the state of the qubits to a simple fiducial ...
user1271772 No more free time's user avatar
8 votes
0 answers
372 views

In D-Wave's universal quantum computer, why does the YY term have to be driven along with the linear X term?

D-Wave has a new prototype annealer that uses a Hamiltonian which, if there was enough qubits and sufficient control, would be able to simulate any universal circuit-based quantum computer with at ...
user1271772 No more free time's user avatar
9 votes
1 answer
122 views

Can a stored programming model be applied to a Quantum Computer?

A stored programming computer model is that where a central memory is used to store both instructions and data that they operate on. Basically all the classical computers of today that follow the von ...
K Sarkar's user avatar
  • 171
3 votes
3 answers
513 views

Are qubits the only elements required to build a quantum computer?

The power of a quantum computer is often described in terms of how many qubits it has. Does that mean that quantum computers can be run using only qubits, and nothing more? Wouldn't we require some ...
Dan Minh Toan's user avatar
6 votes
2 answers
422 views

Randomness from deterministic machine

It is known that in a classical computer we can't generate a purely random number by deterministic process. I am taking a course in Quantum Computing, recently I learnt that using state we can ...
tarit goswami's user avatar