Tag Archives: Shanghai Jiao Tong University

Secure quantum communication network with 15 users

Things are moving quickly where quantum communication networks are concerned. Back in April 2021, Dutch scientists announced the first multi-node quantum network connecting three processors (see my July 8, 2021 posting with the news and an embedded video).

Less than six months later, Chinese scientists announced work on a 15-user quantum network. From a September 23, 2021 news item on phys.org,

Quantum secure direct communication (QSDC) based on entanglement can directly transmit confidential information. Scientist [sic] in China explored a QSDC network based on time-energy entanglement and sum-frequency generation. The results show that when any two users are performing QSDC over 40 kilometers of optical fiber, and the rate of information transmission can be maintained at 1Kbp/s. Our result lays the foundation for the realization of satellite-based long-distance and global QSDC in the future.

A September 23, 2021 Chinese Academy of Sciences (CAS) press release on EurekAlert, which seems to have originated the news item, provides additional detail,

Quantum communication has presented a revolutionary step in secure communication due to its high security of the quantum information, and many communication protocols have been proposed, such as the quantum secure direct communication (QSDC) protocol. QSDC based on entanglement can directly transmit confidential information. Any attack of QSDC results to only random number, and cannot obtain any useful information from it. Therefore, QSDC has simple communication steps and reduces potential security loopholes, and offers high security guarantees, which guarantees the security and the value propositions of quantum communications in general. However, the inability to simultaneously distinguish the four sets of encoded orthogonal entangled states in entanglement-based QSDC protocols limits its practical application. Furthermore, it is important to construct quantum network in order to make wide applications of quantum secure direct communication. Experimental demonstration of QSDC is badly required.

In a new paper published in Light Science & Application, a team of scientists, led by Professor Xianfeng Chen from State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, China and Professor Yuanhua Li from Department of Physics, Jiangxi Normal University, China have explored a QSDC network based on time-energy entanglement and sum-frequency generation (SFG). They present a fully connected entanglement-based QSDC network including five subnets, with 15 users. Using the frequency correlations of the fifteen photon pairs via time division multiplexing and dense wavelength division multiplexing (DWDM), they perform a 40-kilometer fiber QSDC experiment by implying two-step transmission between each user. In this process, the network processor divides the spectrum of the single-photon source into 30 International Telecommunication Union (ITU) channels. With these channels, there will be a coincidence event between each user by performing a Bell-state measurement based on the SFG. This allows the four sets of encoded entangled states to be identified simultaneously without post-selection.

It is well known that the security and reliability of the information transmission for QSDC is an essential part in the quantum network. Therefore, they implemented block transmission and step-by-step transmission methods in QSDC with estimating the secrecy capacity of the quantum channel. After confirming the security of the quantum channel, the legitimate user performs encoding or decoding operations within these schemes reliably.

These scientists summarize the experiment results of their network scheme:

“The results show that when any two users are performing QSDC over 40 kilometers of optical fiber, the fidelity of the entangled state shared by them is still greater than 95%, and the rate of information transmission can be maintained at 1 Kbp/s. Our result demonstrates the feasibility of a proposed QSDC network, and hence lays the foundation for the realization of satellite-based long-distance and global QSDC in the future.”

“With this scheme, each user interconnects with any others through shared pairs of entangled photons in different wavelength. Moreover, it is possible to improve the information transmission rate greater than 100 Kbp/s in the case of the high-performance detectors, as well as high-speed control in modulator being used” they added.

“It is worth noting the present-work, which offers long-distance point-to-point QSDC connection, combined with the recently proposed secure-repeater quantum network of QSDC, which offers secure end-to-end communication throughout the quantum Internet, will enable the construction of secure quantum network using present-day technology, realizing the great potential of QSDC in future communication.” the scientists forecast.

Here’s a link to and a citation for the paper,

A 15-user quantum secure direct communication network by Zhantong Qi, Yuanhua Li, Yiwen Huang, Juan Feng, Yuanlin Zheng & Xianfeng Chen. Light: Science & Applications volume 10, Article number: 183 (2021) DOI: https://doi.org/10.1038/s41377-021-00634-2 Published: 14 September 2021

This paper is open access.

For the profoundly curious, there is an earlier version of this paper on arXiv.org, the site run by Cornell University where it was posted after moderation but prior to peer-review for publication in a journal.

Soft, inflatable, and potentially low-cost neuroprosthetic hand?

An August 16, 2021 news item on ScienceDaily describes a new type of neuroprosthetic,

For the more than 5 million people in the world who have undergone an upper-limb amputation, prosthetics have come a long way. Beyond traditional mannequin-like appendages, there is a growing number of commercial neuroprosthetics — highly articulated bionic limbs, engineered to sense a user’s residual muscle signals and robotically mimic their intended motions.

But this high-tech dexterity comes at a price. Neuroprosthetics can cost tens of thousands of dollars and are built around metal skeletons, with electrical motors that can be heavy and rigid.

Now engineers at MIT [Massachusetts Institute of Technology] and Shanghai Jiao Tong University have designed a soft, lightweight, and potentially low-cost neuroprosthetic hand. Amputees who tested the artificial limb performed daily activities, such as zipping a suitcase, pouring a carton of juice, and petting a cat, just as well as — and in some cases better than — those with more rigid neuroprosthetics.

Here’s a video demonstration,

An August 16, 2021 MIT news news release (also on EurekAlert), which originated the news item, provides more detail,

The researchers found the prosthetic, designed with a system for tactile feedback, restored some primitive sensation in a volunteer’s residual limb. The new design is also surprisingly durable, quickly recovering after being struck with a hammer or run over with a car.

The smart hand is soft and elastic, and weighs about half a pound. Its components total around $500 — a fraction of the weight and material cost associated with more rigid smart limbs.

“This is not a product yet, but the performance is already similar or superior to existing neuroprosthetics, which we’re excited about,” says Xuanhe Zhao, professor of mechanical engineering and of civil and environmental engineering at MIT. “There’s huge potential to make this soft prosthetic very low cost, for low-income families who have suffered from amputation.”

Zhao and his colleagues have published their work today [August 16, 2021] in Nature Biomedical Engineering. Co-authors include MIT postdoc Shaoting Lin, along with Guoying Gu, Xiangyang Zhu, and collaborators at Shanghai Jiao Tong University in China.

Big Hero hand

The team’s pliable new design bears an uncanny resemblance to a certain inflatable robot in the animated film “Big Hero 6.” Like the squishy android, the team’s artificial hand is made from soft, stretchy material — in this case, the commercial elastomer EcoFlex. The prosthetic comprises five balloon-like fingers, each embedded with segments of fiber, similar to articulated bones in actual fingers. The bendy digits are connected to a 3-D-printed “palm,” shaped like a human hand.

Rather than controlling each finger using mounted electrical motors, as most neuroprosthetics do, the researchers used a simple pneumatic system to precisely inflate fingers and bend them in specific positions. This system, including a small pump and valves, can be worn at the waist, significantly reducing the prosthetic’s weight.

Lin developed a computer model to relate a finger’s desired position to the corresponding pressure a pump would have to apply to achieve that position. Using this model, the team developed a controller that directs the pneumatic system to inflate the fingers, in positions that mimic five common grasps, including pinching two and three fingers together, making a balled-up fist, and cupping the palm.

The pneumatic system receives signals from EMG sensors — electromyography sensors that measure electrical signals generated by motor neurons to control muscles. The sensors are fitted at the prosthetic’s opening, where it attaches to a user’s limb. In this arrangement, the sensors can pick up signals from a residual limb, such as when an amputee imagines making a fist.

The team then used an existing algorithm that “decodes” muscle signals and relates them to common grasp types. They used this algorithm to program the controller for their pneumatic system. When an amputee imagines, for instance, holding a wine glass, the sensors pick up the residual muscle signals, which the controller then translates into corresponding pressures. The pump then applies those pressures to inflate each finger and produce the amputee’s intended grasp.

Going a step further in their design, the researchers looked to enable tactile feedback — a feature that is not incorporated in most commercial neuroprosthetics. To do this, they stitched to each fingertip a pressure sensor, which when touched or squeezed produces an electrical signal proportional to the sensed pressure. Each sensor is wired to a specific location on an amputee’s residual limb, so the user can “feel” when the prosthetic’s thumb is pressed, for example, versus the forefinger.

Good grip

To test the inflatable hand, the researchers enlisted two volunteers, each with upper-limb amputations. Once outfitted with the neuroprosthetic, the volunteers learned to use it by repeatedly contracting the muscles in their arm while imagining making five common grasps.

After completing this 15-minute training, the volunteers were asked to perform a number of standardized tests to demonstrate manual strength and dexterity. These tasks included stacking checkers, turning pages, writing with a pen, lifting heavy balls, and picking up fragile objects like strawberries and bread. They repeated the same tests using a more rigid, commercially available bionic hand and found that the inflatable prosthetic was as good, or even better, at most tasks, compared to its rigid counterpart.

One volunteer was also able to intuitively use the soft prosthetic in daily activities, for instance to eat food like crackers, cake, and apples, and to handle objects and tools, such as laptops, bottles, hammers, and pliers. This volunteer could also safely manipulate the squishy prosthetic, for instance to shake someone’s hand, touch a flower, and pet a cat.

In a particularly exciting exercise, the researchers blindfolded the volunteer and found he could discern which prosthetic finger they poked and brushed. He was also able to “feel” bottles of different sizes that were placed in the prosthetic hand, and lifted them in response. The team sees these experiments as a promising sign that amputees can regain a form of sensation and real-time control with the inflatable hand.

The team has filed a patent on the design, through MIT, and is working to improve its sensing and range of motion.

“We now have four grasp types. There can be more,” Zhao says. “This design can be improved, with better decoding technology, higher-density myoelectric arrays, and a more compact pump that could be worn on the wrist. We also want to customize the design for mass production, so we can translate soft robotic technology to benefit society.”

Here’s a link to and a citation for the paper,

A soft neuroprosthetic hand providing simultaneous myoelectric control and tactile feedback by Guoying Gu, Ningbin Zhang, Haipeng Xu, Shaoting Lin, Yang Yu, Guohong Chai, Lisen Ge, Houle Yang, Qiwen Shao, Xinjun Sheng, Xiangyang Zhu, Xuanhe Zhao. Nature Biomedical Engineering (2021) DOI: https://doi.org/10.1038/s41551-021-00767-0 Published: 16 August 2021

This paper is behind a paywall.

Cicada wings for anti-reflective surfaces

This bioinspired piece of research comes courtesy of China. From an Oct. 11, 2016 news item on Nanowerk,

A team of Shanghai Jiao Tong University researchers has used the shape of cicada wings as a template to create antireflective structures fabricated with one of the most intriguing semiconductor materials, titanium dioxide (TiO2). The antireflective structures they produced are capable of suppressing visible light — 450 to 750 nanometers — at different angles of incidence.

An Oct. 11,2016 American Institute of Physics news release, which originated the news item, explains why the researchers focused on cicada wings and how their observations led to a new anti-reflective material,

Why cicada wings? The surfaces of the insect’s wings are composed of highly ordered, tiny vertical “nano-nipple” arrays, according to the researchers. As they report this week in Applied Physics Letters, from AIP Publishing, the resulting biomorphic TiO2 surface they created with antireflective structures shows a significant decrease in reflectivity.

“This can be attributed to an optimally graded refractive index profile between air and the TiO2 via antireflective structures on the surface,” explained Wang Zhang, associate professor at State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University in China.

Small spaces between the ordered nano-antireflective structures “can be thought of as a light-transfer path that let incident light rays into the interior surface of the biomorphic TiO2 — allowing the incident light rays to completely enter the structure,” Zhang continued. “The multiple reflective and scattering effects of the antireflective structures prevented the incident light from returning to the outside atmosphere.”

Significantly, the team’s work relies on “a simple and low-cost sol-gel (wet chemical) method to fabricate biomorphic TiO2 with precise subwavelength antireflective surfaces,” Zhang pointed out. “The TiO2 was a purely anatase phase (a mineral form of TiO2), which has unique antireflective surfaces. This led to an optimally graded refractive index and, ultimately, to angle-dependent antireflective properties within the visible light range.”

In terms of applications, the team’s biomorphic TiO2 antireflective structures “show great potential for photovoltaic devices such as solar cells,” Zhang said. “We expect our work to inspire and motivate engineers to develop antireflective surfaces with unique structures for various practical applications.”

Even after high calcination at 500 C, the antireflective structures retain their morphology and high-performance antireflection properties. These qualities should enable the coatings to withstand harsh environments and make them suitable for long-term applications.

In the future, the team plans “to reduce the optical losses in solar cells by using materials with a higher refractive index such as tantalum pentoxide or any other semiconductor materials,” Zhang said.

I. Photograph and scanning electron microscope characterizations of a black cicada wing (Cryptympana atrata Fabricius). II. Synthesis process of biomorphic TiO2 with ordered nano-nipple array structures. III. Counter map angle-dependent antireflection of biomorphic TiO2 and non-templated TiO2, respectively. CREDIT: Shanghai Jiao Tong University

I. Photograph and scanning electron microscope characterizations of a black cicada wing (Cryptympana atrata Fabricius).
II. Synthesis process of biomorphic TiO2 with ordered nano-nipple array structures.
III. Counter map angle-dependent antireflection of biomorphic TiO2 and non-templated TiO2, respectively.
CREDIT: Shanghai Jiao Tong University

Here’s a link to and a citation for the paper,

Angle dependent antireflection property of TiO2 inspired by cicada wings by Imran Zada, Wang Zhang, Yao Li, Peng Sun, Nianjin Cai, Jiajun Gu, Qinglei Liu, Huilan Su, and Di Zhang.  Appl. Phys. Lett. 109, 153701 (2016); http://dx.doi.org/10.1063/1.4962903

This paper appears to be open access.

Self-assembling, size-specific nanopores or nanotubes mimic nature

I guess you can call this biomimicry or biomimetics as it’s also known. From the  State University of New York at Buffalo  July 17, 2012 news releaseby Charlotte Hsu,

Inspired by nature, an international research team has created synthetic pores that mimic the activity of cellular ion channels, which play a vital role in human health by severely restricting the types of materials allowed to enter cells.

The pores the scientists built are permeable to potassium ions and water, but not to other ions such as sodium and lithium ions.

This kind of extreme selectivity, while prominent in nature, is unprecedented for a synthetic structure, said University at Buffalo chemistry professor Bing Gong, PhD, who led the study.

Here’s how they did it (from the news release),

To create the synthetic pores, the researchers developed a method to force donut-shaped molecules called rigid macrocycles to pile on top of one another. [emphasis mine] The scientists then stitched these stacks of molecules together using hydrogen bonding. The resulting structure was a nanotube with a pore less than a nanometer in diameter.

The July 17, 2012 media advisory by Tona Kunz from the Argonne National Laboratory (one of the partners in this research) describes why creating consistently sized nanopores/nanotubes has been so difficult and offers more information about the macrocycles,

Nanopores and their rolled up version, nanotubes, consist of atoms bonded to each other in a hexagonal pattern to create an array of nanometer-scale openings or channels. This structure creates a filter that can be sized to select which molecules and ions pass into drinking water or into a cell. The same filter technique can limit the release of chemical by-products from industrial processes.

Successes in making synthetic nanotubes from various materials have been reported previously, but their use has been limited because they degrade in water, the pore size of water-resistant carbon nanotubes is difficult to control, and, more critically, the inability to assemble them into appropriate filters.

An international team of researchers, with help of the Advanced Photon Source at Argonne National Laboratory, have succeeded in overcoming these hurdles by building self-assembling, size-specific nanopores. This new capability enables them to engineer nanotubes for specific functions and use pore size to selectively block specific molecules and ions.

Scientists used groupings of atoms called ridged macrocycles that share a planar hexahenylene ethynylene core that bears six amide side chains. Through a cellular self-assembly process, the macrocycles stack cofacially, or atom on top of atom. Each layer of the macrocycle is held together by bonding among hydrogen atoms in the amide side chains. This alignment creates a uniform pore size regardless of the length of the nanotube. A slight misalignment of even a few macrocycles can alter the pore size and greatly compromise the nanotube’s functionality.

Here’s an image of the macrocycles supplied by the Agronne National Labortory,

A snapshot of a helical stack of macryocycles generated in the computer simulation.

The size specificity is  important if  nanopores/nanotubes are going to be used in medical applications,

The pore sizes can be adjusted to filter molecules and ions according to their size by changing the macroycle size, akin to the way a space can be put into a wedding ring to make it fit tighter. The channels are permeable to water, which aids in the fast transmission of intercellular information. The synthetic nanopores mimic the activity of cellular ion channels used in the human body. The research lays the foundation for an array of exciting new technology, such as new ways to deliver directly into cells proteins or medicines to fight diseases.

The research group’s paper has appeared in Nature Communications as of July 17, 2012, from Hsu’s news release,

The study’s lead authors are Xibin Zhou of Beijing Normal University; Guande Liu of Shanghai Jiao Tong University; Kazuhiro Yamato, postdoctoral scientist at UB; and Yi Shen of Shanghai Jiao Tong University and the Shanghai Institute of Applied Physics, Chinese Academy of Sciences. Other institutions that contributed to the work include the University of Nebraska-Lincoln and Argonne National Laboratory. Frank Bright, a SUNY Distinguished Professor of chemistry at UB, assisted with spectroscopic studies.

Self-cleaning clothes

There’s a new cotton fabric that will self-clean when exposed to sunlight. From the Dec. 14, 2011 news item on Nanowerk,

Mingce Long and Deyong Wu say their fabric uses a coating made from a compound of titanium dioxide, the white material used in everything from white paint to foods to sunscreen lotions. Titanium dioxide breaks down dirt and kills microbes when exposed to some types of light. It already has found uses in self-cleaning windows, kitchen and bathroom tiles, odor-free socks and other products. Self-cleaning cotton fabrics have been made in the past, the authors note, but they self-clean thoroughly only when exposed to ultraviolet rays. So they set out to develop a new cotton fabric that cleans itself when exposed to ordinary sunlight.

Their report describes cotton fabric coated with nanoparticles made from a compound of titanium dioxide and nitrogen. They show that fabric coated with the material removes an orange dye stain when exposed to sunlight. Further dispersing nanoparticles composed of silver and iodine accelerates the discoloration process. The coating remains intact after washing and drying.

It’s nice to see that the coating doesn’t wash or dry off easily. Long’s and Wu’s report appears in the ACS [American Chemical Society] Applied Materials & Interfaces (“Realizing Visible-Light-Induced Self-Cleaning Property of Cotton through Coating N-TiO2 Film and Loading AgI Particles”).  Mingce Long is from the  School of Environmental Science and Engineering, Shanghai Jiao Tong University, China  and Deyong Wu is from the School of Chemical and Environmental Engineering, Hubei University for Nationalities, China.

Dexter Johnson of the Nanoclast blog on the IEEE website (Institute of Electrical and Electronics Engineers) notes this in his Dec. 22, 2011 posting,

… This is not just cotton treated with TiO2 but cotton treated with a mix of silver iodide (Agl) along with Nitrogen (N)-TiO2. This combination increased the photocatalytic activities of the material.

So, this is what I find so infuriating about coverage of nanotechnology. Couldn’t someone (besides me) have said that researchers had found a way of improving the photocatalytic performance of TiO2 in textiles so as to make their self-cleaning properties X times better than previous methods?

There you have it from an engineer who’s been the nanotech scene for quite some time. The concept of coating a textile with nanoscale titanium dioxide so it self-cleans is not new; the discovery in this case is a refinement which increased the photocatalytic properties of the textile in question.