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I'm and undergraduate student and I'm doing a report on Quantum computing. As a conclusion of my report I'd like to highlight the latest experimental advances in Quantum Computing, especially in methods like Ion trap and photon polarization. Most of the study I've made is on papers and documents dated 2000 or earlier, so I can't relay on them for this part. I've tried looking to the newest papers i could find online, but they're to specific and detailed and I'm not able to extrapolate something meaningful from them, given the small time I have. I just need to know how far have we come with coherence time, size of networks, number of gates applied et cetera.

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Related: physics.stackexchange.com/q/7412/2451 –  Qmechanic Dec 30 '12 at 19:19
@Qmechanic Your links ask for theory and algorithm, this one ask for experiment. –  hwlau Dec 30 '12 at 19:35
@hwlau: Ups, yeah, you're right. –  Qmechanic Dec 30 '12 at 19:41
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For the complete quantum processors, there is not much progress. In 2001, we can factorize the number $15$ using NMR implementation. Now, eleven years later, we can factorize the number $21$.

Surely, the first experiment is to demonstrate the practicality of the quantum computer so it uses only the simplest implementation that is not necessary scalable. The development after that are more focus on different components that can be scalable when combined together. There are many different implementations and small variations can change the performance pretty much so it is hard to classify them.

The review article of quantum computers has listed the requirements of quantum computer and the pros and crons for each implementation. The following shows the current data for coherence time, number of qubits and storage time. It should be noticed that the

1. Coherence time

The Table 1 in the review articles "Quantum computers" (2010) gives the following values:

  • $T_2\approx 25 s$ for NMR (longest one)
  • $T_2\approx 15 s$ for trapped ions
  • $T_2\approx 0.1 ms$ for infrared photon

where $T_2$ is a measure of decoherent.

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2. Scale of quantum computing

The table 1 in the review articles "Introduction to Quantum Algorithms for Physics and Chemistry" (2012) shows that the scale of two implementations:

  • 6 qubits for Trapped ions
  • 4 qubits for NMR
  • 2 qubits for quantum optics, but 6 quantum walks steps

Note that quantum walks is alternative implementation of quantum computer.

enter image description here

3. Storage time in quantum memory

The table 1 in the review articles "Quantum memories" (2010) shows storage time and the progress of different implementations of quantum memory.

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