For questions about the superconducting realization of quantum computers. Questions can be about both the implementation of this realization or the theory behind this realization. If you are asking about a specific aspect of superconducting quantum computers, please also tag with that (i.e., if you are also asking about the Josephson junction, tag with that).
Questions tagged [superconducting-quantum-computing]
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How does a quantum computer do basic math at the hardware level?
On reading this Reddit thread I realized that even after a couple months of learning about quantum computing I've absolutely no clue about how a quantum computer actually works.
To make the question more precise, let's say we have a superconducting…
Sanchayan Dutta
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Why do optical quantum computers not have to be kept near absolute zero while superconducting quantum computers do?
This is a follow-up question to @heather's answer to the question : Why must quantum computers be kept near absolute zero?
What I know:
Superconducting quantum computing: It is an implementation of a quantum computer in a superconducting electronic…
Sanchayan Dutta
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What is the difference between transmon and Xmon qubits?
Transmon and Xmon qubits are two types of superconducting charge qubits that seem to be often used in superconducting quantum devices.
However, I wasn't able to easily find direct comparisons between them.
The Xmon architecture seems (1304.2322) to…
glS
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What cryogenic systems are suitable for superconducting qubits?
Is a dilution refrigerator the only way to cool superconducting qubits down to 10 millikelvin? If not, what other methods are there, and why is dilution refrigeration the primary method?
auden
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Understanding Google's “Quantum supremacy using a programmable superconducting processor” (Part 1): choice of gate set
I was recently going through the paper titled "Quantum supremacy using a programmable superconducting processor" by NASA Ames Research Centre and the Google Quantum AI team (note that the paper was originally posted on the NASA NTRS but later…
Sanchayan Dutta
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Superconducting qubit researchers: Do your TLS's move?
I have a superconducting system with tens of qubits, each of which can be tuned using DC flux.
One of the main tasks for coherent manipulation of the qubits is to find good idling frequencies and operating points for entangling gates. This effort is…
psitae
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Rotating about the y- or z-axis of the Bloch sphere
In order to rotate about an axis of the Bloch sphere we ususally use pulses e.g. in trapped ion quantum computing or superconducting qubits. Let's say we have rotation around the x-axis. What do I have to change in order to be able to rotate around…
Quasar
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Is there an intuitive way to conceptualize the ground and excited states of a transmon qubit?
I understand how a transmon qubit is analogous to an LC circuit, but has an anharmonic energy spectrum due to the nonlinearity of the Josephson junction. I also understand how to write out the Hamiltonian and the significance of the contributing…
taryn3194
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Understanding Google's “Quantum supremacy using a programmable superconducting processor” (Part 2): simplifiable and intractable tilings
In Google's 54 qubit Sycamore processor, they created a 53 qubit quantum circuit using a random selection of gates from the set $\{\sqrt{X}, \sqrt{Y}, \sqrt{W}\}$ in the following pattern:
FIG 3. Control operations for the quantum supremacy…
Sanchayan Dutta
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What limits scaling down the size of superconducting qubits?
There are multiple ways of building a qubit: Superconducting (transmons), NV-centers/spin-qubits, topological qubits, etc.
The superconducting qubits are the most well-known qubits and are also the easiest to build. The machines by IBM and Google,…
nippon
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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 Hadamard Gate on superconducting circuits nor any…
skan
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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 or lower in frequency?
psitae
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What are the main obstacles to overcome to build silicon-photonic quantum computers?
In superconducting quantum computers, we use mostly superconducting qubits or trapped ions. However, those systems are quite large because their environment either requires near absolute zero temperature (for superconducting to happen), or vacuum…
Aleksandar Kostovic
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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 most polynomial overhead. It was presented at the…
user1271772 No more free time
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Is the Solovay-Kitaev theorem relevant for modern hardware?
The Solovay-Kitaev theorem (and more recent improvements) explains how to efficiently compile any 2-qubit unitary into any universal (dense) finite set of gates. My question is if this theorem is relevant for modern hardware?
Take, for example,…
Nikita Nemkov
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