System Bits: May 16

Quantum-circuit refrigerator; electrochemical water purification; synthetic sensors.

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Refrigerator for quantum computers
Quantum physicist Mikko Möttönen at Aalto University in Finland and his team have invented a quantum-circuit refrigerator, meant to reduce errors in quantum computing.

The research results suggest how harmful errors in quantum computing can be removed — a new twist towards a functioning quantum computer.

The team reminded that quantum computers use quantum bits (qubits) to compute, instead of normal bits, i.e., the bits being crunched in a laptop are either zeros or ones, whereas a qubit can exist simultaneously in both states. This versatility of qubits is a needed for complex computing, but it also makes them sensitive to external perturbations.

Photo of the centimeter-sized silicon chip, which has two parallel superconducting oscillators and the quantum-circuit refrigerators connected to them. (Source: Aalto University)

And, just like today’s processors, quantum computers also need a cooling mechanism especially since in the future it is estimated that thousands or even millions of logical qubits may be simultaneously used in computation. In order to obtain the correct result, every qubit has to be reset in the beginning of the computation, and if the qubits are too hot, they cannot be initialized because they are switching between different states too much. This is the problem Möttönen and his group have developed a solution to.

The nanoscale refrigerator solves a massive challenge: with its help, most electrical quantum devices can be initialized quickly. The devices thus become more powerful and reliable.

Clearing pollutants from water
When it comes to removing very dilute concentrations of pollutants from water, existing separation methods tend to be energy- and chemical-intensive but MIT researchers have developed an electrochemical process to remove even extremely low levels of unwanted compounds.

The new approach is described in a paper by MIT postdoc Xiao Su, Ralph Landau Professor of Chemical Engineering T. Alan Hatton, and five others at MIT and at the Technical University of Darmstadt in Germany.

The system uses a novel method, relying on an electrochemical process to selectively remove organic contaminants such as pesticides, chemical waste products, and pharmaceuticals, even when these are present in small yet dangerous concentrations. The approach also addresses key limitations of conventional electrochemical separation methods, such as acidity fluctuations and losses in performance that can happen as a result of competing surface reactions.

Researchers have developed a new method for removing even extremely low levels of unwanted compounds from water. The new method relies on an electrochemical process to selectively remove organic contaminants such as pesticides, chemical waste products, and pharmaceuticals. (Source: MIT)

In the system, water flows between chemically treated, or “functionalized” surfaces that serve as positive and negative electrodes. These electrode surfaces are coated with what are known as Faradaic materials, which can undergo reactions to become positively or negatively charged. These active groups can be tuned to bind strongly with a specific type of pollutant molecule, as the team demonstrated using ibuprofen and various pesticides. The researchers found that this process can effectively remove such molecules even at parts-per-million concentrations.

Interestingly, the same selective process should also be applied to the recovery of high-value compounds in a chemical or pharmaceutical production plant, where they might otherwise be wasted.

Plug-in synthetic sensor
Although ubiquitous sensors seem almost synonymous with the IoT, some Carnegie Mellon University researchers say sensing with a single, general purpose sensor for each room may be better.

The team has developed a plug-in sensor package that monitors multiple phenomena — sounds, vibration, light, heat, electromagnetic noise, temperature, etc. — in a room. With some help from machine-learning techniques, the sensors can determine whether a faucet’s left or right spigot is running, if the microwave door is open or how many paper towels have been dispensed.

“The idea is you can plug this in and immediately turn a room into a smart environment. You don’t have to go out and buy expensive smart appliances, which probably can’t talk to each other anyway, or attach sensors to everything you want to monitor, which can be hard to maintain as well as ugly. You just plug it into an outlet,” said Gierad Laput, a Ph.D. student in CMU’s Human-Computer Interaction Institute (HCII).

It is an approach that Laput and his co-investigators in HCII’s Future Interfaces Group call ‘synthetic sensors’ because the raw feeds from the unit’s nine sensors can be combined and interpreted in ways that can sense dozens of phenomena of interest.

These findings were presented last week at CHI 2017, the Conference on Human Factors in Computing Systems.