Let's run our circuit on real hardware! We have learned from simulation, from our studies of quantum gates, and from writing quantum scores, what to expect from the output of this circuit. We expect 10000 to be the output. But we also know as we learned in Chapter 3, Quantum States, Quantum Registers, and Measurement, that a real quantum computer is subject to noise. That means that while the vast majority of runs on the quantum computer hardware will output 10000, we expect a percentage of them to output something else. Since the circuit is small, it won't take long to execute, and there is not a lot of time for errors to occur. So the percentage of runs that output something other than 10000 should be small.
Click Run to run the circuit on real hardware. If your circuit has been recently executed by another user, you may then get the option to use their cached results. Don't do that for this example, because we want to run it for ourselves. By default the circuit will be run on identically prepared qubits 1,024 times. This number can be changed via the button next to Run. Run your circuit. Again, as in simulation, you may have to wait and refresh to see when your results are ready. You should also receive an email when the results are ready. This may take a while as there are sometimes users ahead of you in the queue to run on the hardware.
Let's see what the results are:
This is only a portion of the results that fits on screen. Here we see that the vast fraction of the 1,024 runs, 0.754 or 772/1024 runs returned what we expected: 00001, or rewriting in the correct order, 10000. Since we are running on real hardware, each time this percentage may vary. The rest of the 252 runs returned something different, usually off from what we expect by just one bit although not always.
At the bottom of the output, IBM shares the device calibration at the time of the run, including the values for T1 and T2 for each qubit. This will help you get a sense how qubits are prone to error, as the smaller these values, the more error prone a qubit is.