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Please share a paper most recent data on single qubit hardware comparisons. Mainly gate single qubit gate fidelities and coherence times.

Hafiz muhammad Ibrahim jaffar
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2 Answers2

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It's kinda hard to answer this because

  1. There's no universal notion of "best"; a single qubit has many important independent attributes. Even with just the two metrics you pointed out, a qubit can in principle simultaneously have the best gate fidelities and worst coherence times.
  2. Even the gate fidelity metric is flawed, because different gates can have different fidelities.
Cody Wang
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I will add to the answer by Cody Wang, as indeed there are many parameters that one needs to consider when picking out "the best" quantum hardware for a task.

Usually, high coherence times mean that the quibts are well "isolated" so that, amongst other things (heat, crosstalk etc.), they will tend not to couple to their environments (i.e. no magnetic or electric interferences). This is good in the sense that quantum states can be maintained for longer and therefore used in longer computations, in quantum memory for long-range quantum communication etc. however, being "isolated" also means that interacting with the qubits becomes challenging which is a problem for fast and accurate quantum computations. To my knowledge, the current state of the art, when it comes to long coherence, is in solid-state quantum devices namely Silicone spin qubits or Nitrogen vacancy centres (NVs). Here is a link to a paper with some of the longest coherence times (with dynamical decoupling) observed for NVs: https://arxiv.org/abs/1905.02094

Gate fidelities are usually limited by coherence times. (Which doesn't mean that long coherence = high fidelity as stated earlier) I would have a tendency at looking at hardware/papers in superconducting qubits, quantum dots, or photonic qubits if you're searching for fast and accurate quantum gates.

Timour
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