Journal: Nature Communications

Article Title: Perfect absorption in complex scattering systems with or without hidden symmetries

doi: 10.1038/s41467-020-19645-5

Figure Lengend Snippet: A PNA-X (network analyzer with two internal sources) is used to generate microwaves with well-defined frequency and relative amplitudes at the two ports as the CPA state excitation signals. Coherent phase control between the two excitation signals is realized by placing a phase shifter between port 2 of the network analyzer and the graph. The outgoing and returning waves are directly measured by the PNA-X. On the right side of the figure is the tetrahedral microwave graph formed by coaxial cables and Tee-junctions. The four-way adapter shown in the figure is realized by connecting two Tee-junctions together in the real experiment. One node of the graph is loaded with a variable attenuator to provide parametric variation of the scattering system. One other node is made from either a Tee-junction (TRI) or a 3-port circulator (BTRI) to create a TRI system or a broken TRI system, respectively.

Article Snippet: On one node of the graph, two Tee-junctions form a four-way adapter where a voltage variable attenuator (HMC346ALC3B from Analog Devices, Inc.) is connected to one connector.

Techniques: Control

Journal: Nature Communications

Article Title: Perfect absorption in complex scattering systems with or without hidden symmetries

doi: 10.1038/s41467-020-19645-5

Figure Lengend Snippet: Plots are normalized so that CPA conditions are in the center of the parameter variation range. The closest frequency CPA condition for the simulation is plotted along with the experimental data. a Measured ratio of output power P out to input power P in as the microwave frequency sent into both ports of the graph is simultaneously swept near the CPA frequency ( Δ f = f − f CPA ). Inset shows the output-to-input power ratio response for a larger frequency range around the resonance, and the dashed box corresponds to the frequency range shown in a . The output-to-input power ratio shows a sharp dip close to 10 −5 at the CPA frequency ( f CPA ) in both experiment and simulation. The scale bar of the mean mode spacing Δ is shown in the plot for reference. b Output-to-input power ratio obtained by varying the attenuation of the variable attenuator in the graph, while the other waveform characteristics (CPA frequency and waveform) are equal to the ones set in a . Δ Att is the attenuation normalized by Att CPA from the CPA condition. Inset shows the absorption difference between the attenuator only and the attenuator embedded in the graph. Output-to-input power ratio obtained by changing the amplitude A ( c ) and phase difference Δ ϕ ( d ) separately of the two excitation signals required for the CPA state. The absorption of power reaches its maximum at the CPA configuration, and quickly deteriorates for even small offset from the CPA condition. All experimental results are obtained by direct measurement of the input and output RF powers.

Article Snippet: On one node of the graph, two Tee-junctions form a four-way adapter where a voltage variable attenuator (HMC346ALC3B from Analog Devices, Inc.) is connected to one connector.

Techniques:

Journal: Nature Communications

Article Title: Perfect absorption in complex scattering systems with or without hidden symmetries

doi: 10.1038/s41467-020-19645-5

Figure Lengend Snippet: Plots are normalized so that CPA conditions are in the center of the parameter variation range. The closest CPA frequency condition for the simulation is plotted along with the experimental data. a Measured ratio of output power P out to input power P in as the microwave frequency sent into both ports of the graph is simultaneously swept near the CPA frequency ( Δ f = f − f CPA ). Inset shows the output-to-input power ratio response for a larger frequency range around the resonance, and the dashed box corresponds to the frequency range shown in a . The output-to-input power ratio shows a sharp dip below 10 −5 at the CPA frequency ( f CPA ) in both experiment and simulation. The scale bar of the mean mode spacing Δ is shown in the plot for reference. b Output-to-input power ratio obtained by varying the attenuation of the variable attenuator in the graph, while the other waveform characteristics (CPA frequency and waveform) are equal to the ones set in a . Δ Att is the attenuation normalized by Att CPA from the CPA condition. Output-to-input power ratio obtained by changing the amplitude A ( c ) and phase difference Δ ϕ ( d ) separately of the two excitation signals required for the CPA state. All experimental results are obtained by direct measurement of the input and output RF powers.

Article Snippet: On one node of the graph, two Tee-junctions form a four-way adapter where a voltage variable attenuator (HMC346ALC3B from Analog Devices, Inc.) is connected to one connector.

Techniques:

Journal: Nature Communications

Article Title: Perfect absorption in complex scattering systems with or without hidden symmetries

doi: 10.1038/s41467-020-19645-5

Figure Lengend Snippet: a Schematic of the microwave graph with labeled ports under CPA condition at 2.2999 GHz in simulation. b Voltage profiles of four nodes in the graph under CPA condition. c Power distribution among the graph components under the CPA condition. Left plot shows that about 80% of the power are being dissipated on the attenuator, while the remainder is dissipated in the uniformly attenuated cables. Right plot shows reactive power on the cables and short circuit. Compare with the "Anti-CPA" condition in Supplementary Fig. .

Article Snippet: On one node of the graph, two Tee-junctions form a four-way adapter where a voltage variable attenuator (HMC346ALC3B from Analog Devices, Inc.) is connected to one connector.

Techniques: Labeling