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Quantum Computer

01 /Quantum Computers 02 /How to build a qubit 03 /Spin qubits (beginner level) 04 /Operations on spin qubits (beginner level) 05 /Electron spin qubits 06 /Capturing a single electron 07 /Quantum dot qubits 08 /Quantum control and readout 09 /Qubit errors 10 /NV center qubits 11 /Operations on NV center qubits 12 /The Transmon Qubit - A basis for the Quantum Computer 13 /Operations on the Transmon Qubit - Circuit QED 14 /Single-qubit operations on the Transmon qubit 15 /Measurements on the Transmon Qubit 16 /Two-qubit operations on the Transmon qubit 17 /Topological qubits: Anyons 18 /Operations on anyons: Braiding 19 /Operations on anyons: Real-life experiments 20 /Topological quantum computing: Majorana fermions and where to find them 21 /Majorana bound states in superconductors 22 /How do you measure Majorana bound states? 23 /A framework for the future Quantum Computer 24 /The Building Blocks of a Quantum Computer 25 /How to build a Quantum Algorithm - Quantum Circuits 26 /How do you program a quantum algorithm? 27 /The compiler of a quantum computer 28 /Micro-architectures 29 /How do we connect our quantum system to a classical interface? 30 /Assembling a Quantum Processor 31 /Microwave drivers for qubits 32 /Implementation of microwave drivers 33 /Quantum error correction 34 /Surface codes 35 /Fault-tolerant Quantum Error Correction with surface codes

Measurements on the Transmon Qubit

What is the point in running a quantum algorithm if you do not know the outcome? This video will be the first of three on how we can control superconducting - or transmon  - qubits. Niels Butink will start explaining the way we read out the state of the qubit, which we do using a readout resonator. While doing this, he introduces an important concept, the readout fidelity of the measurement. 

After single-qubit readout, Niels briefly touches upon how current state-of-the-art quantum processors measure multiple qubits at the same time. We will see that we need to make smart use of multiplexed signals. Let’s get started!

Prerequisite knowledge

Further thinking

 We have seen that in order to measure one qubit, a resonator coupled to it is used. When having multiple qubits, resonators with different resonance frequencies are needed. Can you identify each qubit and its resonator in the circuit shown during the video? We see in the picture there are more resonators than qubits, what do you think is the purpose of these?

Solution

Further reading

In the video, Niels advises several articles for further reading. You can also first watch the entire series on transmon qubits (6 videos in total) and come back to this. 

Advanced pulse shaping

Benchmarking and improving superconducting amplifiers

Advanced readout topologies