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Category: computing

On computing quantum waves exactly from classical action

The fundamental quantum postulates on the existence of a wave function, its propagation with the Schrödinger equation in theorem 3.2 and the wave collapse at a measurement in lemma 3.3 are derived from the classical theorem 2.4. Furthermore, analytic computations of the classical action are simpler than solving the Feynman path integral and potentially easier than solving the Schrödinger equation directly. In addition, theorem 3.2 is a multi-particle result.

The J classical multipaths in theorem 3.2 and lemma 3.3 are strictly determined by the initial and final conditions. In the double slit experiment, the probabilistic quantum observation results from the non-Lipschitz constraint force in the slit. For the harmonic oscillator, the Coulomb wave, the particle in the box, or the spinning particle, the initial probabilistic density distribution is classically propagated forward in time. In the EPR experiment [64,65], theorem 2.4 determines a constant angular momentum χo↑,χo↓ over time, and lemma 3.3 in turn allows a classical interpretation that the decision which spin correlation is sensed behind the filters is already taken when the particles separate.

Quantum chips could scale faster with new spin-qubit readout that reduces sensors and wiring

Quantum computers, devices that process information leveraging quantum mechanical effects, could tackle some tasks that are difficult or impossible to solve using classical computers. These systems represent data as qubits, units of information that can exist in multiple states at once, unlike the bits used by classical computers that represent data using binary values (“0” or “1”).

Some of the quantum computers developed in recent years store quantum information in the spin (i.e., intrinsic angular momentum) of electrons or nuclei that are trapped in small semiconductor-based structures, known as quantum dots. For these devices to operate reliably, however, engineers need to be able to precisely measure the quantum states of the spin qubits they rely on, a process that is known as qubit readout. It would also be advantageous for these states to be precisely measured in a way that is architecturally compact, or in other words, using space-efficient hardware as opposed to numerous bulkier components.

Researchers at Quantum Motion and University College London (UCL) recently introduced a new approach to clearly read out the states of spin qubits leveraging high-frequency electrical signals. This method, introduced in a paper published in Nature Electronics, was developed by Jacob F. Chittock-Wood and his colleagues while he was completing his Ph.D. at UCL.

New 3D device harnesses living brain cells for computing

Princeton researchers have combined brain cells and advanced electronics into a single 3D device that can be programmed to recognize patterns using computational techniques. Past attempts at using brain cells to do computation have relied on 2D cultures grown in a petri dish or 3D clusters that are probed and monitored from outside. The Princeton device takes a different approach, working from the inside out.

Using advanced fabrication techniques, the team created a 3D mesh made of microscopic metal wires and electrodes supported by a thin epoxy coating. Because the coating is so thin, it has just the right amount of flexibility to interface with the soft neurons that grow around it. The team used the mesh as a scaffold to culture tens of thousands of neurons into a vast 3D network that can be used to do computation.

The study was published in Nature Electronics on Apr. 23.

Excuse me, is that solar panel pointing in the right direction?

On a bright morning, graduate student Jeremy Klotz and professor Shree Nayar walked through upper Manhattan with a tall tripod and a camera that takes 360-degree images. Their route took them to bike docking stations, which use solar energy to power their kiosks, docking mechanisms, wireless communication, and even E-bike recharging in recent installations. At each docking station, the researchers raised the camera above the panel, snapped a spherical picture, and sent it to Klotz’s laptop.

Seconds later, the team’s computer vision program told them something remarkable: how much energy that panel would generate in a year—and how much it could generate if it were pointed at the optimal angle.

As it turns out, the solar panels powering the bike docking stations—and likely many solar panels across New York City and other urban destinations—may be leaving significant energy untapped simply because they are not at their best orientation.

Soundwaves settle debate about elusive quantum particle

It was a head-spinning discovery. In 2018, researchers in Japan claimed to find concrete evidence of an elusive particle, a Majorana fermion, in a quantum spin liquid called ruthenium trichloride. Majoranas are highly sought-after by quantum materials scientists because when a pair are localized, or trapped, they can securely encode information and form a stable qubit—the building block of quantum computing.

Some researchers heralded the finding and used it to launch their own studies, while others believed the breakthrough—which was made by measuring what’s called the thermal Hall effect—was actually a mirage caused by defects in the material sample.

Cornell researchers have now waded into the debate and their findings, published in Nature, show both camps were wrong. By measuring the movement of sound waves rather than the flow of heat, the team discovered the thermal Hall effect was caused by rotating lattice vibrations called chiral phonons.

Microfluidic chip reveals how living glioblastoma slices resist chemotherapy

Combining microchip engineering techniques with cutting-edge gene profiling, scientists at Columbia University have developed a new way to study drug responses in living slices of human brain tumor cells. The system, using a type of chip called a microfluidic device, has already revealed new details about how these aggressive tumors resist chemotherapy drugs and could help researchers develop more effective treatments.

The work grew from earlier efforts to study glioblastoma tumors removed from patients during surgery. “These samples that we’re getting from our colleagues who resect these tumors clinically, they’re alive, and we can actually do experiments directly on those surgical samples,” says Peter Sims, Ph.D., associate professor of systems biology at Columbia and senior author on the new study, which appears in the journal Lab on a Chip.

New memory chip survives temperatures hotter than lava

The electronics inside your phone, your car, and every satellite currently orbiting Earth share one critical weakness: heat. Push them past about 200 degrees Celsius and they start to fail. For decades, that thermal ceiling has been one of the hardest walls in engineering. Now a team at the University of Southern California may have just found a way around it.

In a study published in Science, researchers led by Joshua Yang, Arthur B. Freeman Chair Professor at the Ming Hsieh Department of Electrical and Computer Engineering of the USC Viterbi School of Engineering and the USC School of Advanced Computing, report a new type of electronic memory device that kept working reliably at 700 degrees Celsius, hotter than molten lava and far beyond anything previously achieved in its class. The device showed no signs of reaching its limit. Seven hundred degrees was simply as hot as their testing equipment could go.

“You may call it a revolution,” Yang said. “It is the best high-temperature memory ever demonstrated.”

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