# Tag Info

14

It's just a coincidence. I can speak from personal recollection on the Google side. Google originally intended to use a 72 qubit chip (Bristlecone) where qubits were essentially directly connected to each other. They then switched to an architecture where qubits were connected indirectly via a coupler. The coupler requires a control line, so this increased ...

8

They have different error rates because they are two different physical devices! This relates to the manufacturing processes of these chips. Every device is unique and will have its own fingerprint meaning its own error rate. Of course this is not something that manufactures do on purpose, but a side effect of making these qubit devices. It’s very difficult ...

7

In the classical case, there is a pretty big difference between digital computers and analogue ones. The methodology and hardware is very much distinct (in all cases I know of, at least). The divide is still there in the quantum case, but it doesn't run quite as deep. The hardware can be similar, but requirements on how it behaves and how to manipulate it ...

6

It depends on what you mean by "able to handle". You mention a circuit depth of 99, which might be possible, but what will be the fidelity of the final state with respect to the one it's supposed to be (assuming no decoherence)? If your fidelity requirement is close to 100%, the maximum circuit depth that the IBM machines can handle, is zero (try just ...

4

From the public data given by IBM about IBM Q16 Melbourne (14 qubits available): Mean gate error: $2.14 \times 10^{-3}$ (probably higher for CX and lower for 1-qubit gates, but this information seems to be no longer available). Mean measure error: $2.68\times 10^{-2}$. If your circuit contains $300$ gates then the probability that at least one gate fails ...

4

The choice of gates is entirely dependent on the types of interactions that occur in the different architectures. The cross resonance gate used by IBM generates the ZX interaction you want (plus other stuff) that leads to a CNOT. Trapped ions have XX type interactions that give rise to Molmer Sorensen gates. For single qubit gates it depends on what driving ...

4

I am going to try to give guesses that can make sense: More qubits does not mean better machines. They may be less noise-tolerant and with less connectivity between qubits. That is why, when you benchmark them (with or without error-correction), you look first at the simplest implementations of state of art algorithms. Plus, you may change some calibrations ...

4

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Basically being IBM Q Network member give you the possibility to access IBM’s most-powerful quantum computing systems through the cloud (currently 20Q, 27Q, 28Q, 53Q devices with Quantum Volume between 8 and 32 depending the device). Some of the premium devices are visible in this post: https://www.ibm.com/blogs/research/2020/07/qv32-performance/ Depending ...

3

No output shows for your code as you have a line underneath the call to plot_histogram(). This should be the last line of the section in the Jupyter notebook if you would like the image to be displayed. I was able to run your code by removing the final line (print(counts)) and it displayed the histogram below.

3

When referring to the commercial quantum computers of both parties, it is that both are based on a different quantum principles. The D-Wave machine works via quantum annealing and is suited for optimization problems. The machine by IBM is a gate-based quantum computer, similar to how digital computers work at the elementary level. As the two quantum ...

3

The Q-Object not valid error you received is caused by the amount of shots you set. The max shots allowed is 8192. Since the amount of shots you set (16384) is greater than the max amount of shots allowed, you get that error. The TranspilerError is caused by the second format for layout. When I tested your code with the second layout, I received this error ...

3

There is a link on the qiskit website to the public Slack. Here you can find channels for talking the various elements of Qiskit and also the IBM Q Experience.

3

So, to begin, I would point out that the 500 micosec T1 time is for a single qubit in isolation, while the GHZ results are on a 20 qubit device. This device has an avg T1 time of around ~75 microsec. The GHZ results were done by Ken Wei from IBM, and will be published shortly. In short, the circuit is a standard GHZ building circuit, with a hadamard ...

3

I was recently looking for a similar solution. Hope this helps. job = execute(qc, backend=backend, shots=1024) results = job.result() print(results.time_taken) You can also check all the values stored in result as it is a dictionary by printing it: print(results) Here you can check for all the information that is available within the dictionary and you ...

3

results.get_data() was replaced by results.data(). The new function returns (almost) the same information, but the runtime attribute was removed. As far as I know, there is no official way to get the runtime of your job on the computer. There are some ways to get it through your own code, but keep in mind these are not official methods of doing so, and the ...

2

My guess is that this is an example of co-opetition, i.e. collaborative competition. Number of qubits is just a single characteristic of a quantum processor, but there are a lot more, like tolerance, topology, etc. Also this characteristic is the only one that most people understand. Thus it's not reasonable to put all the resources on the increasing just ...

2

To simulate a 3D material, the material's structure will need to be somewhat understood. That way the structure can be mapped to the qubit connectivity. Notice in this tutorial the qubits and their connections to each other are represented in graphs. The 3D material to be simulated can be put into a graph that will then be mapped to the qubit graph and the ...

2

I would add that thermic noise, radiocative background (mainly cosmic rays) can play role in different error rate as those noise sources are different for each quantum processor. Moreover, as a user of IBM Q, you probably know that quantum processors are sometimes under maintenance. Since each processor is maintained in different time, their runtime is ...

2

Well actually when looking at the source code, the construct_circuit method: quantum register where the sequential QFT is performed self._up_qreg = QuantumRegister(2 * self._n, name='up') # quantum register where the multiplications are made self._down_qreg = QuantumRegister(self._n, name='down') # auxiliary quantum register used in ...

2

The ibmq_qasm_simulator is a cloud-based simulator. You need to say from qiskit import IBMQ provider = IBMQ.load_account() sim = provider.backends.ibmq_qasm_simulator

2

This link was shared in the Qiskit Global Summer School Discord channel. https://join.slack.com/t/qiskit/shared_invite/zt-fybmq791-hYRopcSH6YetxycNPXgv~A I hope this works for you!

2

If you don't have the ability to perform the controlled-not directly between a pair of qubits, then you simply need to swap the qubits to place them onto a pair of qubits which can have a controlled-not applied to them.

2

For interactions between non-nearest neighbour qubits, ancilla qubits are required, together with SWAP gates. The state of one of the (in this case) two qubits is swapped with the ancilla. This operation is repeated until the qubits are NN, and then the interaction can take place. After this is done, then the state of the ancilla is swapped back with the ...

2

I'm not sure what your specific question is - the IBM Q processor does not implement an error correction scheme by default, so the theorem doesn't apply. Furthermore, the statistic provided in the Wikipedia page suggests this chip would be incapable of sufficiently depressing the error rate: At a 0.1% probability of a depolarizing error, the surface code ...

1

The could be a problem, but it depends on how you're realising your qubits. Some realisations are configured so that $E_0=E_1$, and then there's no problem. There is (at least from the theoretical perspective) a simple fix: if you're supposed to be waiting a time $t$, then, instead: wait time $t/2$ apply bit flip wait time $t/2$ apply bit flip. This ...

1

It is always difficult to force classical algorithms to quantum devices. And this is maybe a signal that quantum algorithms should be something different and new. Actually, quantum systems have unique properties like entanglement, that classical systems don't have. However, look at the following paper for a study on the relation between fuzzy and quantum ...

1

This is not an error, there are two messages here and they are both just warnings. The first Credentials are already in use error means that you have called load_account() when you already had an account loaded. The second message, DeprecationWarning, is letting you know that a method that you are using will be removed in a future version of Qiskit and ...

1

All the machines are in New York so it does not matter which one you pick.

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There is no hub simply called ibm-q. I think what you are meaning to do is provider = IBMQ.get_provider(). What you put in the brackets is the name of the hub, for example if your school was a registered hub you might have something to write in there but most users will leave the brackets blank. After this you can do backend = provider.get_backend(...

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