Questions tagged [physical-realization]

For questions about physical implementations of a quantum algorithm or other quantum information protocol. DO NOT use for questions about simulation or emulation of quantum computers, or cloud-based quantum computing services like the IBM Q Experience.

Filter by
Sorted by
Tagged with
5
votes
1answer
46 views

How do we know that a superconducting circuit is a quantum system?

In introductions to superconducting qubits, we often take the classical LC circuit and then quantize the operators. Why are we allowed to do this? I do not see this derivation anywhere -- what ...
3
votes
1answer
42 views

How are gates implemented in a transmon qubit?

A transmon qubit is fundamentally in LC circuit. How are gates implemented in a transmon qubit? How do we know what voltage corresponds to the $\sigma_x$ gate for example?
5
votes
1answer
43 views
+50

In a transmon qubit, what corresponds to the ground and excited states?

In a transmon qubit, we have ground and energy eigenstates but what is actually happening in the circuit here? How do the current and voltage look? It looks like its made up of things you would find ...
2
votes
1answer
32 views

What are the typical gate times for single-qubit and 2-qubit gates for ion trap, superconducting, neutral atom, photonic, spin QC?

What are the typical gate times for single-qubit and 2-qubit gates for -- ion trap, -- superconducting, -- neutral atom, -- photonic, -- spin quantum computers based on today's technologies?
1
vote
0answers
26 views

How many physical qubits are needed to encode a logical qubit on ion trap, superconducting, neutral atom, photonic QC?

How many physical qubits are needed to encode a logical qubit on an -- ion trap, -- superconducting, -- neutral atom, -- photonic, -- spin quantum computer based on today's technologies?
1
vote
0answers
36 views

What are useful abstraction levels for external quantum input/output of quantum computers?

Section "2.2.3 Quantum measurement" in Nielsen&Chuang uses very general measurement axioms: Postulate 3: Quantum measurements are described by a collection $\{M_m\}$ of measurement ...
-1
votes
1answer
42 views

How to implement gate which is like Identity but multiplied on "i"

In my program I need a single qubit processing gate which implements logic like this: |0> ==> i*|0> |1> ==> i*|1> This is like Identity gate but multiplied on "i" I ...
4
votes
2answers
77 views

What are introductory resources to learn about quantum computing hardware?

I am interested in learning some details of quantum computers inner working, what are the limitation etc. in order to understand quantum computation more. Can some one refer me to some good materials ...
5
votes
2answers
162 views

Quantum communications and "knowledge" of receiving a qubit

Question from a computer scientist (not a physicist). Imagine two nodes on a quantum network. Alice sends Bob a qubit in some state of superposition over a quantum channel. Is Bob able to sense that ...
5
votes
1answer
53 views

What does it mean for a channel to be independent of the input state?

A 2007 paper shows how to construct quantum channels on finite-dimensional Hilbert spaces $$\sigma=\Phi(\rho)=\sum_i K_i \rho K_i^\dagger,\qquad \sum_i K_i^\dagger K_i=\mathbb{I}$$ for which $\Phi(\...
5
votes
1answer
34 views

Do individual qubits on IBM quantum processors share the same control unit?

I want to investigate the maximum possible parallelism of quantum operations on a specific IBM device (such as the latest heavy-hex architecture), which requires a basic knowledge of their control ...
3
votes
1answer
53 views

How to obtain control and drift Hamiltonians for device in Qiskit?

I would like to play around with Qiskit OpenPulse and the publicly available IBMQ quantum computer that supports OpenPulse. My humble goal is to use Qutip's optimal control libraries to get a pulse ...
2
votes
1answer
123 views

How to formulate Dynamical Decoupling passes in Qiskit to improve result upon circuit execution

First, let me say that I am not familiar with the idea of Dynamical Decoupling. The goal of this question is to understand how to set up a circuit with dynamical decoupling to improve my hardware ...
8
votes
0answers
100 views

How can time crystals be useful in qRAM design?

A time crystal is a phase of a matter which is ordered in time, similar to classical crystals which are ordered spatially. In other words, the structure of a time crystal is ever-changing but with ...
1
vote
0answers
87 views

What is the justification for the use of this arbitrary post-processing vector?

I am reading through this paper which describes the use of a post-processing vector $\vec{c}$ with elements having values of $(-1,0,1)$. In equation 3 they give their solution as a linear combination ...
2
votes
2answers
54 views

Does QRNG generates True Random numbers?

I read an article that claims, QRNG can produce a true random number. So I wonder, how could they prove that this is a true random numbers generator? In fact, imagine I look at my memory state and ...
3
votes
3answers
757 views

Why do we have to measure the circuit before sending it to the real quantum computer?

If I want to run a circuit on a real quantum computer, I have to measure it before running it. For example: ...
3
votes
0answers
36 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 ...
1
vote
1answer
568 views

What does a quantum logic gate look like in a universal quantum computer?

I am familiar with logic gates which are in classical computers. They are made up of semiconductor devices like diodes and transistors. There are some companies which are working on the universal ...
2
votes
0answers
36 views

What is an electro-optic switch?

I found an implementation of a CNOT in photonic QC and I just couldn't find any info on a component named "electro-optic switch" What does it do exactly? How does it work? The ...
5
votes
1answer
87 views

Why is entanglement creation difficult?

No matter from the true physical realization to date or from some papers, it seems that multipartite entanglement creation is difficult. However, the circuit showing below can easily create ...
2
votes
0answers
20 views

What are the most popular QND measurement implementations used in photonic quantum computers?

What components are used in order to perform QND measurement in photonic quantum computers?
4
votes
2answers
54 views

How does measuring in the $|\pm\rangle$ basis works in experiments?

I don't get how measuring in different bases works in experiments. From an experimental point of view, what do we do to measure in $|\pm \rangle$ basis? If I'm getting it right measuring in the ...
1
vote
0answers
23 views

Is this QEC scheme technology dependant? [closed]

Is this [1] type of error correction also usable for ion-trap based quantum computers? Is it quantum technology dependent? [1] P. Das et al., “A Scalable Decoder Micro-architecture for Fault-Tolerant ...
1
vote
0answers
129 views

Does a quantum computer exist today? [closed]

I agree that this may not be an easy question to answer. But lately, I increasingly come across the fact that many news materials and research papers in the field of quantum technologies say that at ...
2
votes
1answer
55 views

Is it possible to perform quantum computation between different Hilbert spaces?

Let us consider a protocol between Alice and Bob. Alice works in a $2^n$-dimensional Hilbert space $\mathcal{H}_A$, using $n$ qubits. Bob works in a $(1+2^n)$-dimensional Hilbert space using qdits. ...
4
votes
1answer
58 views

Quantum computer speedups for classically efficient applications

I'm interested in learning about cases where a quantum computer could be used to perform tasks with only a constant (albeit large) factor of improvement in execution speed over classical computers. ...
0
votes
1answer
67 views

Is it possible to design a Quantum Computing Advantage to deploy an application on the web?

I need to understand the frontier and practical applications of quantum computing. Is it possible to design a Quantum Computing Advantage to deploy an application on the web, such as a browser, ...
6
votes
1answer
135 views

Claimed "potential revenue" from machine learning in 2023?

In this plot: taken from here, IonQ is claiming to have a potential application in machine learning by 2023. What applications could they have in mind? From what I understand, modern error correction ...
2
votes
0answers
17 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 $...
2
votes
0answers
31 views

Crosstalk error of simultaneous cnots

We can use simultaneous randomized benchmarking (SRB) to quantify the crosstalk impact of simultaneous CNOTs. The crosstalk error is caused by many reasons, for example, the always-on ZZ interaction, ...
1
vote
1answer
50 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 ...
4
votes
1answer
132 views

How significant is achieving electronic transport in a single qubit at room temperature?

This is a follow-up to a previous question I asked: How promising is the possibility of carbon-based qubits to make a qubit that’s stable at room temperature? I am trying to assess the significance of ...
2
votes
1answer
77 views

How is the Grover iteration realized in an actual quantum circuit?

The number of the Grover's diffuser iterations is proportional to square root of the amount of input data, but how is this realized when building a real quantum circuit? Is it simply by concatenating ...
2
votes
0answers
34 views

How to do the counting when computing the fault tolerant threshold of quantum codes?

Here, I want to ask a basic question about how to compute the fault tolerance threshold of quantum codes. As I know, maybe, the most usual way is to do some simulations. Howvever, I am more intersted ...
4
votes
2answers
140 views

Is it possible to have access to real quantum computers that have more than 15 qubits for my master thesis?

My physics master thesis is about variational quantum optimization and I have to run algorithms with more qubits than 15. Is it possible to make any requests to use larger IBM real quantum computers?
4
votes
2answers
70 views

Up to date overview of experimental approaches to quantum computing

I'm interested in getting an overview of the leading approaches to quantum computing from a physics perspective. I've read most of Nielsen and Chuang, but its chapter on physical realizations looks ...
2
votes
0answers
36 views

What are Sideband Pulses

I see sideband pulses used all over the place when looking up implementation techniques especially in Trapped Ion QC. Is there a layman's explanation of what they actually are? I understand what they ...
5
votes
2answers
421 views

Topology graphs of IBM's quantum computers

What is the meaning of the topology graphs of IBM's quantum computers? How should it be interpreted? For example, how should I understand the following graph?
3
votes
0answers
56 views

Are there any detailed designs for Quantum Computing hardware?

I am looking to analyze some quantum hardware designs, preferably superconducting and photonics, but I can't seem to find sources that give some detailed information. Can someone provide me designs ...
5
votes
0answers
74 views

How do we realise photonic gates?

I am interested in photonic computing, and I am curious how the gates work. I once saw a picture of a photonic CNOT gate that used just mirrors and polarizers. I have not been able to find any ...
2
votes
2answers
98 views

Is there a quantum processor with physically implemented Toffoli gate?

Recently, I came across the article Realization of efficient quantum gates with a superconducting qubit-qutrit circuit where its authors proposed a physical implementation of three qubits quantum ...
2
votes
1answer
93 views

How do quantum computers implement a random unitary gate?

If I from qiskit.quantum_info import random_unitary and then random_unitary(2**number_of_qubits) What returns is a unitary ...
2
votes
1answer
36 views

Is Grovers Algorithm Oracle creation a hardware level aspect?

There are numerous questions that asks about practical application demonstration of the Grover algorithm for arrays and databases. However examples are not seen anywhere. While searching for its ...
2
votes
2answers
106 views

Can the (universal) state inversion operator be physically realized?

I was trying to solve an exercise from Vazirani's course "Qubits, Quantum Mechanics and Computers": A mathematically nice, but unphysical, way to detect entanglement is to use the state ...
3
votes
3answers
299 views

How are the IBM's and Google's Hadamard gates fabricated and operated?

There are thousands of articles, books and web sites describing the Hadamard Gate from a theoretical point of view. But I haven't been able to find any photo about any real implementeation of a ...
3
votes
1answer
56 views

Gate characteristics of different platforms

I would like to know if there is a place in which is summarized the gate characteristics of the different quantum computer existing (IBM,Google, others). For instance, which kind of two qubit gate ...
1
vote
1answer
76 views

Average execution time for T gate

Using the Q# resource estimator, I found out that my program, meant to do graph coloring using Grover's algorithm, could be decomposed into ~500-1000*x T gates, where x in the number of iterations, ...
1
vote
0answers
37 views

How can I achieve single-qubit $T$ operation using spin resonance?

We know that $T$ gate is as follows $T=\left(\begin{array}{cc}1 & 0 \\ 0 & e^{i \pi / 4}\end{array}\right)$ And on the other resultant spin-resonance hamiltonian is $\frac{H}{\hbar}=\frac{1}{2}...
4
votes
2answers
165 views

Is there a straightforward way to calculate the quantum volume for simple systems?

There are a few people who ask how to calculate IBM's "quantum volume", but it's not clear what the actual mathematical definition of this is. In the answers here, people just point to ...