PDF (double-sided) - Physics Department, UCSB - University of ...
Share Embed Flag
Download ePaper

PDF (double-sided) - Physics Department, UCSB - University of ...

PDF (double-sided) - Physics Department, UCSB - University of ... PDF (double-sided) - Physics Department, UCSB - University of ...

web.physics.ucsb.edu
from web.physics.ucsb.edu More from this publisher
27.09.2014 Views

equires to converge. Since the algorithm has much less built-in “smart” decision making, it needs to draw its information from more data. But due to its pipelineability and thus higher duty cycle, it does not run for much longer than the Nelder-Mead Simplex algorithm before it converges. 11.4 Experimental Results Even though the main result of the experiment consists of only the obtained S-value together with its standard deviation, this number needs to be supplemented with several datasets that test the experiment for flaws. The most useful of this additional information are the parameters of the sequence found by the optimization, since angles that match the theoretically expected values are a strong indication that the implementation can be trusted. To claim a reliable violation, the dataset should further address all known mechanism for the introduction of artificial correlations during the time of measurement, e.g. microwave and measurement crosstalk. Additional checks that show the variation of S as a function of certain parameters can be of assistance in debugging the experiment, but are of lesser importance for proving its correctness due to the robustness of the inequality. Finally, to explain the obtained S-value, the performance parameters of the involved qubits (and resonator), like T 1 and T 2 , can be used in a simulation 258

Table 11.6: Qubit Sample Parameters – Capacitive Coupling Implementation Parameter Value Qubit A: T 1 340 ns Visibility 85.8% Qubit B: T 1 480 ns Visibility 85.3% Coupling: Swap Frequency 11.4 MHz Measurement Crosstalk ∼ 10% to create an error budget for the experiment. 11.4.1 Capacitive Coupling For the capacitively coupled sample, the optimization yielded an S-value of 1.816 (see Table 11.7) for the sequence parameters shown in Table 11.8. As expected from theory, the two measurements on each qubit are roughly perpendicular (α−α ′ ≈ 73 ◦ −(−16 ◦ ) = 89 ◦ and β −β ′ ≈ 168 ◦ −82 ◦ = 86 ◦ ). The phases of the rotation pulses, i.e. the planes in which the qubits are measured, seem less correct at first glance. But it is hard to come to a reliable conclusion since φ a ′ and φ b 259

Table 11.6: Qubit Sample Parameters – Capacitive Coupling Implementation<br />

Parameter<br />

Value<br />

Qubit A:<br />

T 1<br />

340 ns<br />

Visibility 85.8%<br />

Qubit B:<br />

T 1<br />

480 ns<br />

Visibility 85.3%<br />

Coupling:<br />

Swap Frequency 11.4 MHz<br />

Measurement Crosstalk ∼ 10%<br />

to create an error budget for the experiment.<br />

11.4.1 Capacitive Coupling<br />

For the capacitively coupled sample, the optimization yielded an S-value <strong>of</strong><br />

1.816 (see Table 11.7) for the sequence parameters shown in Table 11.8. As expected<br />

from theory, the two measurements on each qubit are roughly perpendicular<br />

(α−α ′ ≈ 73 ◦ −(−16 ◦ ) = 89 ◦ and β −β ′ ≈ 168 ◦ −82 ◦ = 86 ◦ ). The phases <strong>of</strong> the<br />

rotation pulses, i.e. the planes in which the qubits are measured, seem less correct<br />

at first glance. But it is hard to come to a reliable conclusion since φ a ′<br />

and φ b<br />

259

logo

products

Resources

Company

Terms of service
Privacy policy
Cookie policy
Cookie settings
Imprint
Change language
Made with love in Switzerland
© 2024 Yumpu.com all rights reserved

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!