Monthly Archives: March 2017

Even Ordinary Computer Users Could Access Secret Quantum Computing

You may not need a quantum computer of your own to securely use quantum computing in the future. For the first time, researchers have shown how even ordinary classical computer users could remotely access quantum computing resources online while keeping their quantum computations securely hidden from the quantum computer itself.

Tech giants such as Google and IBM are racing to build universal quantum computers that could someday analyze millions of possible solutions much faster than today’s most powerful classical supercomputers. Such companies have also begun offering online access to their early quantum processors as a glimpse of how anyone could tap the power of cloud-based quantum computing. Until recently, most researchers believed that there was no way for remote users to securely hide their quantum computations from prying eyes unless they too possessed quantum computers. That assumption is now being challenged by researchers in Singapore and Australia through a new paper published in the 11 July issue of the journal Physical Review X.

“Frankly, I think we are all quite surprised that this is possible,” says Joseph Fitzsimons, a theoretical physicist for the Centre for Quantum Technologies at the National University of Singapore and principal investigator on the study. “There had been a number of results showing that it was unlikely for a classical user to be able to hide [delegated quantum computations] perfectly, and I think many of us in the field had interpreted this as evidence that nothing useful could be hidden.”

The technique for helping classical computer users hide their quantum computations relies upon a particular approach known as measurement-based quantum computing. Quantum computing’s main promise relies upon leveraging quantum bits (qubits) of information that can exist as both 1s and 0s simultaneously—unlike classical computing bits that exist as either 1 or 0. That means qubits can simultaneously represent and process many more states of information than classical computing bits.

In measurement-based quantum computing, a quantum computer puts all its qubits into a particular state of quantum entanglement so that any changes to a single qubit affect all the qubits. Next, qubits are individually measured one by one in a certain order that specifies the program being run on the quantum computer. A remote user can provide step-by-step instructions for each qubit’s measurement that encode both the input data and the program being run. Crucially, each measurement depends on the outcome of previous measurements.

Fitzsimons and his colleagues figured out how to exploit this step-wise approach to quantum computing and achieve a new form of “blind quantum computation” security. They showed how remote users relying on classical computers can hide the meaning behind each step of the measurement sequence from the quantum computer performing the computation. That means the owner of the quantum computer cannot tell the role of each measurement step and which qubits were used for inputs, operations, or outputs.

The Real Future of Quantum Computing?

Instead of creating quantum computers based on qubits that can each adopt only two possible options, scientists have now developed a microchip that can generate “qudits” that can each assume 10 or more states, potentially opening up a new way to creating incredibly powerful quantum computers, a new study finds.

Classical computers switch transistors either on or off to symbolize data as ones and zeroes. In contrast, quantum computers use quantum bits, or qubits that, because of the bizarre nature of quantum physics, can be in a state of superposition where they simultaneously act as both 1 and 0.

The superpositions that qubits can adopt let them each help perform two calculations at once. If two qubits are quantum-mechanically linked, or entangled, they can help perform four calculations simultaneously; three qubits, eight calculations; and so on. As a result, a quantum computer with 300 qubits could perform more calculations in an instant than there are atoms in the known universe, solving certain problems much faster than classical computers. However, superpositions are extraordinarily fragile, making it difficult to work with multiple qubits.

Most attempts at building practical quantum computers rely on particles that serve as qubits. However, scientists have long known that they could in principle use qudits with more than two states simultaneously. In principle, a quantum computer with two 32-state qudits, for example, would be able to perform as many operations as 10 qubits while skipping the challenges inherent with working with 10 qubits together.

Now scientists have for the first time created a microchip that can generate two entangled qudits each with 10 states, for 100 dimensions total, more than what six entangled qubits could generate. “We have now achieved the compact and easy generation of high-dimensional quantum states,” says study co-lead author Michael Kues, a quantum optics researcher at Canada’s National Institute of Scientific Research, or INRS, its French acronym, in Varennes, Quebec.

The researchers developed a photonic chip fabricated using techniques similar to ones used for integrated circuits. A laser fires pulses of light into a micro-ring resonator, a 270-micrometer-diameter circle etched onto silica glass, which in turn emits entangled pairs of photons. Each photon is in a superposition of 10 possible wavelengths or colors.

“For example, a high-dimensional photon can be red and yellow and green and blue, although the photons used here were in the infrared wavelength range,” Kues says. Specifically, one photon from each pair spanned wavelengths from 1534 to 1550 nanometers, while the other spanned from 1550 to 1566 nanometers.

Western Digital WD1402A UART

Gordon Bell is famous for launching the PDP series of minicomputers at Digital Equipment Corp. in the 1960s. These ushered in the era of networked and interactive computing that would come to full flower with the introduction of the personal computer in the 1970s. But while minicomputers as a distinct class now belong to the history books, Bell also invented a lesser known but no less significant piece of technology that’s still in action all over the world: The universal asynchronous receiver/transmitter, or UART.

UARTs are used to let two digital devices communicate with each other by sending bits one at a time over a serial interface without bothering the device’s primary processor with the details.

Today, more sophisticated serial setups are available, such as the ubiquitous USB standard, but for a time UARTs ruled supreme as the way to, for example, connect modems to PCs. And the simple UART still has its place, not least as the communication method of last resort with a lot of modern network equipment.

The UART was invented because of Bell’s own need to connect a Teletype to a PDP-1, a task that required converting parallel signals into serial signals. He cooked up a circuit that used some 50 discrete components. The idea proved popular and Western Digital, a small company making calculator chips, offered to create a single-chip version of the UART. Western Digital founder Al Phillips still remembers when his vice president of engineering showed him the Rubylith sheets with the design, ready for fabrication. “I looked at it for a minute and spotted an open circuit,” Phillips says. “The VP got hysterical.” Western Digital introduced the WD1402A around 1971, and other versions soon followed.

Low-Cost Pliable Materials Transform Glove Into Sign-to-Text Machine

Researchers have made a low-cost smart glove that can translate the American Sign Language alphabet into text and send the messages via Bluetooth to a smartphone or computer. The glove can also be used to control a virtual hand.

While it could aid the deaf community, its developers say the smart glove could prove really valuable for virtual and augmented reality, remote surgery, and defense uses like controlling bomb-diffusing robots.

This isn’t the first gesture-tracking glove. There are companies pursuing similar devices that recognize gestures for computer control, à la the 2002 film Minority Report. Some researchers have also specifically developed gloves that convert sign language into text or audible speech.

What’s different about the new glove is its use of extremely low-cost, pliable materials, says developer Darren Lipomi, a nanoengineering professor at the University of California, San Diego. The total cost of the components in the system reported in the journal PLOS ONE cost less than US $100, Lipomi says. And unlike other gesture-recognizing gloves, which use MEMS sensors made of brittle materials, the soft stretchable materials in Lipomi’s glove should make it more robust.

The key components of the new glove are flexible strain sensors made of a rubbery polymer. Lipomi and his team make the sensors by cutting narrow strips from a super-thin film of the polymer and coating them with conductive carbon paint.

Then they use a stretchy glue to attach nine sensors on the knuckles of an athletic leather glove, two on each finger and one on the thumb. Thin, stainless steel threads connect each sensor to a circuit board attached at the wrist. The board also has an accelerometer and a Bluetooth transmitter.