Engineers design ‘living materials’ | MIT News Office

Engineers design ‘living materials’ | MIT News Office: By programming cells to produce different types of curli fibers under certain conditions, the researchers were able to control the biofilms’ properties and create gold nanowires, conducting biofilms, and films studded with quantum dots...

“It’s a really simple system but what happens over time is you get curli that’s increasingly labeled by gold particles. It shows that indeed you can make cells that talk to each other and they can change the composition of the material over time,” Lu says. “Ultimately, we hope to emulate how natural systems, like bone, form. No one tells bone what to do, but it generates a material in response to environmental signals.”

Quantum communication controlled by resonance in 'artificial atoms'

Quantum communication controlled by resonance in 'artificial atoms': "We capture the electrons in 'boxes'. Each box consist of a quantum dot, which is an artificial atom. The quantum dots are embedded in the semiconductor and each quantum dot can capture one electron. There needs to be three quantum dots next to each other using nanometer-scale electrostatic metal gates. When we open contact between the 'boxes' the electrons can sense each others' presence. The three spins must coordinate their orientations because it cost extra energy to put electrons with the same spin into the same box. To lower their energy, they not only spread out among the three boxes, but they orient their spins to further lower their energy. The three boxes together form a single entity – a qubit or quantum bit," explains Marcus.

An electrical signal is now sent from outside and by rapidly opening the boxes the system begins to swing in dynamic vibrations. The researchers can use this to change the quantum state of the electrons. "By combining three electrons in a triple quantum dot and oscillating an applied electric field at the frequency that separates adjacent energy levels, we can thus control the spins of the electrons without measuring them," explains Charles Marcus.

Physicists build quantum refrigerator based on four quantum dots

Physicists build quantum refrigerator based on four quantum dots: The proposed system consists of four quantum arranged in a square configuration, which the researchers call a "quadridot." The scientists theoretically showed that this quadridot acts as a quantum refrigerator when coupled to four independent reservoirs (one hot, one cold, and two of intermediate temperature). The quadridot pumps energy in the form of electrons from the hot reservoir and the cold reservoir to the intermediate-temperature reservoirs. When properly tuned, the quadridot can cool the quantum dot in contact with the cold reservoir to a temperature that is lower than its original temperature.
This configuration overcomes one of the biggest difficulties in realizing self-contained quantum refrigerators, which is engineering the interaction among the hot-, cold-, and intermediate-temperature reservoirs. The quantum dot array provides a relatively simple way to achieve this three-body interaction that may be possible to experimentally realize in the future.

Quantum Dots Make Artificial Photosynthesis Last Longer

Quantum Dots Make Artificial Photosynthesis Last Longer: ...One approach involves using particles that combine light-absorbing materials with catalysts that can split water. But the light-absorbing materials tend to deteriorate quickly in sunlight, rendering the approach impractical.

In the latest issue of the journal Science, researchers from the University of Rochester show that quantum dots not only absorb the light but also are far more durable than previous light-absorbing materials. The new approach also has the advantage of not requiring any precious metals, so it might be relatively cheap.

Quantum dots control brain cells for the first time

Quantum dots control brain cells for the first time: First, they cultivated prostate cancer cells on a film covered with quantum dots. The cell membranes of the cancer cells were positioned next to the dots. The team then shone light onto the nanoparticles.

Energy from the light excites electrons within the quantum dot which causes the surrounding area to become negatively charged (see diagram). This caused some of the cancer cells' ion channels, which are mediated by a voltage, to open, allowing ions to rush in or out of the cells...

When Lin's team repeated their experiment with nerve cells, they found that stimulating the quantum dots caused ion channels to open and the nerve cell to fire.