Quantum Internet Update: Quantum entanglement works through 50 km of optical fiber

One could envisage building the world’s first intercity light-matter quantum network in the coming years. (Credit: IQOQI Innsbruck/Harald Ritsch)

For the first time, a team led by Innsbruck physicist Ben Lanyon has sent a light particle entangled with matter over 50 km of optical fiber. This paves the way for the practical use of quantum networks and sets a milestone for a future quantum internet.

The quantum internet promises absolutely tap-proof communication and powerful distributed sensor networks for new science and technology. However, because quantum information cannot be copied, it is not possible to send this information over a classical network. Quantum information must be transmitted by quantum particles, and special interfaces are required for this. The Innsbruck-based experimental physicist Ben Lanyon, who was awarded the Austrian START Prize in 2015 for his research, is researching these important intersections of a future quantum Internet. Now his team at the Department of Experimental Physics at the University of Innsbruck and at the Institute of Quantum Optics and Quantum Information of the Austrian Academy of Sciences has achieved a record for the transfer of quantum entanglement between matter and light. For the first time, a distance of 50 kilometers was covered using fiber optic cables. “This is two orders of magnitude further than was previously possible and is a practical distance to start building inter-city quantum networks,” says Ben Lanyon.

Converted photon for transmission

Lanyon’s team started the experiment with a calcium atom trapped in an ion trap. Using laser beams, the researchers write a quantum state onto the ion and simultaneously excite it to emit a photon in which quantum information is stored. As a result, the quantum states of the atom and the light particle are entangled. But the challenge is to transmit the photon over fiber optic cables. “The photon emitted by the calcium ion has a wavelength of 854 nanometers and is quickly absorbed by the optical fiber”, says Ben Lanyon. His team therefore initially sends the light particle through a nonlinear crystal illuminated by a strong laser. Thereby the photon wavelength is converted to the optimal value for long-distance travel: the current telecommunications standard wavelength of 1550 nanometers. The researchers from Innsbruck then send this photon through a 50-kilometer-long optical fiber line. Their measurements show that atom and light particle are still entangled even after the wavelength conversion and this long journey.

Even greater distances in sight

As a next step, Lanyon and his team show that their methods would enable entanglement to be generated between ions 100 kilometers apart and more. Two nodes send each an entangled photon over a distance of 50 kilometers to an intersection where the light particles are measured in such a way that they lose their entanglement with the ions, which in turn would entangle them. With 100-kilometer node spacing now a possibility, one could therefore envisage building the world’s first intercity light-matter quantum network in the coming years: only a handful of trapped ion-systems would be required on the way to establish a quantum internet between Innsbruck and Vienna, for example.

Learn more: Entan­gle­ment sent over 50 km of opti­cal fiber

 

The Latest on: Quantum internet
  • Current encryption algorithms still strong, NIST official says
    on December 6, 2019 at 12:53 pm

    NIST is currently working on a number of initiatives to develop more-modern cryptographic algorithms – ones that resist codebreaking efforts from quantum computers as well as new standards for smaller ...

  • AWS Crowdsources Its Quantum Computing Future
    on December 6, 2019 at 6:56 am

    For the most part, quantum computing hype is far ahead of reality. Quantum computers may be available to experiment with over the internet and through cloud services like AWS Braket. But they are ...

  • This Week in Tech: What on Earth Is a Quantum Computer?
    on December 6, 2019 at 6:00 am

    Quantum computers manipulate qubits with exquisite control ... Instagram now requires birth dates from all users as it tries to protect young people from the dark side of the internet. So said Reuters ...

  • Quantum Trends And The Internet of Things
    on December 5, 2019 at 4:53 pm

    There is an additional “entanglement” relating to quantum, and that is its intersection with the Internet of Things (IoT). Loosely defined, the Internet of Things (IoT) refers to the general idea of ...

  • NIST official says post-quantum environment still years away
    on December 5, 2019 at 12:23 pm

    Despite recent industry claims of quantum supremacy ... computers as well as new standards for smaller "lightweight" and internet-of-things devices that have become more prevalent over the ...

  • China steals U.S.-funded quantum research
    on December 4, 2019 at 1:57 pm

    Quantum technology and computing provide extremely secure ... represents our nation’s future is being stolen right before our eyes.” China’s Sina.com internet site for the first time revealed Tehran’s ...

  • Amazon offers quantum computing on its AWS servers
    on December 3, 2019 at 4:10 pm

    ... which up until now has been pretty quiet on the quantum front -- has plans to offer a quantum computing service to companies through the internet, thereby eliminating some of the costs and other ...

  • Amazon is now offering quantum computing as a service
    on December 2, 2019 at 3:20 pm

    its attempt to turn the nascent field of quantum computing into a service you can access over the internet, a month after Microsoft did something similar. “Amazon Braket is a fully managed AWS service ...

  • Qubits on the Move: QuTech and the Quantum Internet
    on December 2, 2019 at 1:01 pm

    One such idea was the focus of a plenary at the conference: the creation of a quantum internet. Ronald Hanson, Scientific Director at the QuTech research institute and a professor at the Delft ...

  • Amazon Joins Tech’s Great Quantum Computing Race
    on December 2, 2019 at 4:30 am

    Amazon is not the first to launch a quantum cloud service either. IBM has offered access to its own quantum hardware over the internet since 2016 and Google says it will soon do the same. Microsoft, ...

via  Bing News

 

One more step to a super-secure quantum internet

via MIT Review

Scientists have managed to send a record-breaking amount of data in quantum form, using a strange unit of quantum information called a qutrit.

The news: Quantum tech promises to allow data to be sent securely over long distances. Scientists have already shown it’s possible to transmit information both on land and via satellites using quantum bits, or qubits. Now physicists at the University of Science and Technology of China and the University of Vienna in Austria have found a way to ship even more data using something called quantum trits, or qutrits.

Qutrits? Oh, come on, you’ve just made that up: Nope, they’re real. Conventional bits used to encode everything from financial records to YouTube videos are streams of electrical or photonic pulses than can represent either a or a 0. Qubits, which are typically electrons or photons, can carry more information because they can be polarized in two directions at once, so they can represent both a and a at the same time. Qutrits, which can be polarized in three different dimensions simultaneously, can carry even more information. In theory, this can then be transmitted using quantum teleportation.
Quantum … what? Quantum teleportation is a method for shipping data that relies on an almost-mystical phenomenon called entanglement. Entangled quantum particles can influence one another’s state, even if they are continents apart. In teleportation, a sender and receiver each receive one of a pair of entangled qubits. The sender measures the interaction of their qubit with another one that holds data they want to send. By applying the results of this measurement to the other entangled qubit, the receiver can work out what information has been transmitted. (For a more detailed look at quantum teleportation, see our explainer here.)

Measuring progress: Getting this to work with qubits isn’t easy—and harnessing qutrits is even harder because of that extra dimension. But the researchers, who include Jian-Wei Pan, a Chinese pioneer of quantum communication, say they have cracked the problem by tweaking the first part of the teleportation process so that senders have more measurement information to pass on to receivers. This will make it easier for the latter to work out what data has been teleported over. The research was published in the journal Physical Review Letters.

Deterring hackers: This might seem rather esoteric, but it has huge implications for cybersecurity. Hackers can snoop on conventional bits flowing across the internet without leaving a trace. But interfering with quantum units of information causes them to lose their delicate quantum state, leaving a telltale sign of hacking. If qutrits can be harnessed at scale, they could form the backbone of an ultra-secure quantum internet that could be used to send highly sensitive government and commercial data.

Learn more: A super-secure quantum internet just took another step closer to reality

 

The Latest on: Quantum internet
  • Current encryption algorithms still strong, NIST official says
    on December 6, 2019 at 12:53 pm

    NIST is currently working on a number of initiatives to develop more-modern cryptographic algorithms – ones that resist codebreaking efforts from quantum computers as well as new standards for smaller ...

  • AWS Crowdsources Its Quantum Computing Future
    on December 6, 2019 at 6:56 am

    For the most part, quantum computing hype is far ahead of reality. Quantum computers may be available to experiment with over the internet and through cloud services like AWS Braket. But they are ...

  • This Week in Tech: What on Earth Is a Quantum Computer?
    on December 6, 2019 at 6:00 am

    Quantum computers manipulate qubits with exquisite control ... Instagram now requires birth dates from all users as it tries to protect young people from the dark side of the internet. So said Reuters ...

  • Quantum Trends And The Internet of Things
    on December 5, 2019 at 4:53 pm

    There is an additional “entanglement” relating to quantum, and that is its intersection with the Internet of Things (IoT). Loosely defined, the Internet of Things (IoT) refers to the general idea of ...

  • NIST official says post-quantum environment still years away
    on December 5, 2019 at 12:23 pm

    Despite recent industry claims of quantum supremacy ... computers as well as new standards for smaller "lightweight" and internet-of-things devices that have become more prevalent over the ...

  • China steals U.S.-funded quantum research
    on December 4, 2019 at 1:57 pm

    Quantum technology and computing provide extremely secure ... represents our nation’s future is being stolen right before our eyes.” China’s Sina.com internet site for the first time revealed Tehran’s ...

  • Amazon offers quantum computing on its AWS servers
    on December 3, 2019 at 4:10 pm

    ... which up until now has been pretty quiet on the quantum front -- has plans to offer a quantum computing service to companies through the internet, thereby eliminating some of the costs and other ...

  • Amazon is now offering quantum computing as a service
    on December 2, 2019 at 3:20 pm

    its attempt to turn the nascent field of quantum computing into a service you can access over the internet, a month after Microsoft did something similar. “Amazon Braket is a fully managed AWS service ...

  • Qubits on the Move: QuTech and the Quantum Internet
    on December 2, 2019 at 1:01 pm

    One such idea was the focus of a plenary at the conference: the creation of a quantum internet. Ronald Hanson, Scientific Director at the QuTech research institute and a professor at the Delft ...

  • Amazon Joins Tech’s Great Quantum Computing Race
    on December 2, 2019 at 4:30 am

    Amazon is not the first to launch a quantum cloud service either. IBM has offered access to its own quantum hardware over the internet since 2016 and Google says it will soon do the same. Microsoft, ...

via  Bing News

 

A major step towards a quantum internet

Figure. Schematic image of the spin detection of a circularly polarized photon exciting an electron spin. The yellow nano-fabricated metal electrodes form the pockets required to trap the electrons, move them, and sense them.

A research team led by Osaka University demonstrated how information encoded in the circular polarization of a laser beam can be translated into the spin state of an electron in a quantum dot, each being a quantum bit and a quantum computer candidate. The achievement represents a major step towards a “quantum internet,” in which future computers can rapidly and securely send and receive quantum information.

Quantum computers have the potential to vastly outperform current systems because they work in a fundamentally different way. Instead of processing discrete ones and zeros, quantum information, whether stored in electron spins or transmitted by laser photons, can be in a superposition of multiple states simultaneously. Moreover, the states of two or more objects can become entangled, so that the status of one cannot be completely described without this other. Handling entangled states allow quantum computers to evaluate many possibilities simultaneously, as well as transmit information from place to place immune from eavesdropping.

However, these entangled states can be very fragile, lasting only microseconds before losing coherence. To realize the goal of a quantum internet, over which coherent light signals can relay quantum information, these signals must be able to interact with electron spins inside distant computers.

Researchers led by Osaka University used laser light to send quantum information to a quantum dot by altering the spin state of a single electron trapped there. While electrons don’t spin in the usual sense, they do have angular momentum, which can be flipped when absorbing circularly polarized laser light.

“Importantly, this action allowed us to read the state of the electron after applying the laser light to confirm that it was in the correct spin state,” says first author Takafumi Fujita. “Our readout method used the Pauli exclusion principle, which prohibits two electrons from occupying the exact same state. On the tiny quantum dot, there is only enough space for the electron to pass the so-called Pauli spin blockade if it has the correct spin.”

Quantum information transfer has already been used for cryptographic purposes. “The transfer of superposition states or entangled states allows for completely secure quantum key distribution,” senior author Akira Oiwa says. “This is because any attempt to intercept the signal automatically destroys the superposition, making it impossible to listen in without being detected.”

The rapid optical manipulation of individual spins is a promising method for producing a quantum nano-scale general computing platform. An exciting possibility is that future computers may be able to leverage this method for many other applications, including optimization and chemical simulations.

Learn more: Travelling towards a quantum internet at light speed

 

The Latest on: Quantum internet
  • Current encryption algorithms still strong, NIST official says
    on December 6, 2019 at 12:53 pm

    NIST is currently working on a number of initiatives to develop more-modern cryptographic algorithms – ones that resist codebreaking efforts from quantum computers as well as new standards for smaller ...

  • AWS Crowdsources Its Quantum Computing Future
    on December 6, 2019 at 6:56 am

    For the most part, quantum computing hype is far ahead of reality. Quantum computers may be available to experiment with over the internet and through cloud services like AWS Braket. But they are ...

  • This Week in Tech: What on Earth Is a Quantum Computer?
    on December 6, 2019 at 6:00 am

    Quantum computers manipulate qubits with exquisite control ... Instagram now requires birth dates from all users as it tries to protect young people from the dark side of the internet. So said Reuters ...

  • Quantum Trends And The Internet of Things
    on December 5, 2019 at 4:53 pm

    There is an additional “entanglement” relating to quantum, and that is its intersection with the Internet of Things (IoT). Loosely defined, the Internet of Things (IoT) refers to the general idea of ...

  • NIST official says post-quantum environment still years away
    on December 5, 2019 at 12:23 pm

    Despite recent industry claims of quantum supremacy ... computers as well as new standards for smaller "lightweight" and internet-of-things devices that have become more prevalent over the ...

  • China steals U.S.-funded quantum research
    on December 4, 2019 at 1:57 pm

    Quantum technology and computing provide extremely secure ... represents our nation’s future is being stolen right before our eyes.” China’s Sina.com internet site for the first time revealed Tehran’s ...

  • Amazon offers quantum computing on its AWS servers
    on December 3, 2019 at 4:10 pm

    ... which up until now has been pretty quiet on the quantum front -- has plans to offer a quantum computing service to companies through the internet, thereby eliminating some of the costs and other ...

  • Amazon is now offering quantum computing as a service
    on December 2, 2019 at 3:20 pm

    its attempt to turn the nascent field of quantum computing into a service you can access over the internet, a month after Microsoft did something similar. “Amazon Braket is a fully managed AWS service ...

  • Qubits on the Move: QuTech and the Quantum Internet
    on December 2, 2019 at 1:01 pm

    One such idea was the focus of a plenary at the conference: the creation of a quantum internet. Ronald Hanson, Scientific Director at the QuTech research institute and a professor at the Delft ...

  • Amazon Joins Tech’s Great Quantum Computing Race
    on December 2, 2019 at 4:30 am

    Amazon is not the first to launch a quantum cloud service either. IBM has offered access to its own quantum hardware over the internet since 2016 and Google says it will soon do the same. Microsoft, ...

via  Bing News

 

A global quantum encryption network speeds nearer

Researchers developed a fiber optic device that can switch the polarization of light more than 1 billion times per second. The device could be useful for quantum encryption data transmission in free-space links.
Credit: Marco Avesani, University of Padova

Robust encoder switches polarization 1 billion times a second; could facilitate global quantum encryption network

Researchers have developed a simple and stable device to generate the quantum states necessary for quantum key distribution. The device could make it more practical to develop a global data network that uses this very secure method of encryption to protect everything from credit card transactions to texts.

New encryption techniques are needed because computers powerful enough to crack today’s algorithm-based encryption codes will likely be available in the next decade or two. Rather than relying on math, quantum key distribution uses quantum properties of light such as polarization to encode and send a random key needed to decrypt encoded data. The method is exceptionally secure because any third-party intrusion is detectable.

In the Optical Society (OSA) journal Optics Letters, researchers from the University of Padova in Italy report that their all-fiber device can switch the polarization of light more than 1 billion times per second. The device is also self-compensating, making it insensitive to temperature and other environmental changes.

“Quantum key distribution is expected to have a deep impact in the privacy and security of citizens,” said Giuseppe Vallone, who led this research within the QuantumFuture research group coordinated by co-author Paolo Villoresi. “Our scheme simplifies quantum key distribution for free-space communication — such as from satellites to Earth or between moving terminals— which is required to achieve a global quantum network.”

Developing a global network

Because quantum encryption doesn’t work well over long-distance fiber networks there is now a push to develop a satellite-based quantum communication network to link various ground-based quantum encryption networks around the world.

Although various properties of light can be used to create quantum states for quantum encryption, polarization is particularly well suited for free-space links because it is not perturbed by the atmosphere and the decoding at the receiver can be performed without the challenging task of funneling the data into single mode fiber.

“Our goal is to develop a quantum encryption scheme to use between a satellite and the ground, where the keys are generated in orbit,” said Vallone. “However, today’s polarization encoders aren’t ideal for use in space because they are unstable, expensive and complex. They can even exhibit side-channels that undermine the security of the protocol.”

Fast and stable polarization encoding

The new polarization encoder — which the researchers call POGNAC for POlarization SaGNAC — can rapidly rotate the polarization of incoming laser light thanks to a fiber-loop Sagnac interferometer. This setup splits the light into two beams whose polarizations are at right angles relative to each other. The beams then travel through the fiber-loop in clockwise and counterclockwise directions. The current components could fit into a package measuring 15 X 5 x 5 centimeters, with further miniaturization possible if smaller components were incorporated.

Inside the fiber loop, the researchers used a commercially available electro-optics modulator to change the polarization to create the quantum states necessary for quantum key distribution. Because the clockwise and anticlockwise components arrive to the modulator at different times, they can each be modulated independently.

Modulators use an applied voltage to change the optical phase. However, the absolute value of the phase shift depends on many parameters that change with time. “In the POGNAC, only the relative shift between the two polarization components is relevant – this relative phase shift corresponds to a change in output polarization – while shifts that arise from temperature changes and other factors are self-corrected,” said Vallone. “This makes the POGNAC very stable and eliminates polarization drifts that have affected other devices.”

The researchers tested their new device by measuring the polarization of quantum states generated by the POGNAC and comparing them with the expected values. They measured an intrinsic quantum bit error rate (QBER) as low as 0.2 %, well below the 1-2 percent QBER of typical quantum key distribution systems.

“Our results show that data can be encoded using the polarization of light in a simple and efficient way,” said Vallone. “We were able to accomplish this using only commercially available components.”

The researchers are continuing to improve on their approach and plan to perform further tests to see how the POGNAC performs when encoding quantum keys for encryption.

Learn more: New All-Fiber Device Simplifies Free-space Based Quantum Key Distribution

 

The Latest on: Global quantum encryption network

via  Bing News

 

A device that could serve as the backbone of a future quantum Internet

Professor Hoi-Kwong Lo (ECE) and his collaborators have performed a proof-of-principle experiment on a key aspect of all-photonic quantum repeaters (Photo: Jessica MacInnis)

U of T Engineering researchers have demonstrated proof-of-principle for a device that could serve as the backbone of a future quantum Internet. Professor Hoi-Kwong Lo (ECE, Physics) and his collaborators have developed a prototype for a key element for all-photonic quantum repeaters, a critical step in long-distance quantum communication.

A quantum Internet is the ‘Holy Grail’ of quantum information processing, enabling many novel applications including information-theoretic secure communication. Today’s Internet was not specifically designed for security, and it shows: hacking, break-ins and computer espionage are common challenges. Nefarious hackers are constantly poking holes in sophisticated layers of defence erected by individuals, corporations and governments.

In light of this, researchers have proposed other ways of transmitting data that would leverage key features of quantum physics to provide virtually unbreakable encryption. One of the most promising technologies involves a technique known as quantum key distribution (QKD). QKD exploits the fact that the simple act of sensing or measuring the state of a quantum system disturbs that system. Because of this, any third-party eavesdropping would leave behind a clearly detectable trace, and the communication can be aborted before any sensitive information is lost.

Until now, this type of quantum security has been demonstrated in small-scale systems. Lo and his team are among a group of researchers around the world who are laying the groundwork for a future quantum Internet by working to address some of the challenges in transmitting quantum information over great distances, using optical fibre communication.

Because light signals lose potency as they travel long distances through fibre-optic cables, devices called repeaters are inserted at regular intervals along the line. These repeaters boost and amplify the signals to help transmit the information along the line.

But quantum information is different, and existing repeaters for quantum information are highly problematic. They require storage of the quantum state at the repeater sites, making the repeaters much more error prone, difficult to build, and very expensive because they often operate at cryogenic temperatures.

Lo and his team have proposed a different approach. They are working on the development of the next generation of repeaters, called all-photonic quantum repeaters, that would eliminate or reduce many of the shortcomings of standard quantum repeaters. With collaborators at Osaka University, Toyama University and NTT Corporation in Japan, Lo and his team have demonstrated proof-of-concept of their work in a paper recently published in Nature Communications.

“We have developed all-photonic repeaters that allow time-reversed adaptive Bell measurement,” says Lo. “Because these repeaters are all-optical, they offer advantages that traditional — quantum-memory-based matter — repeaters do not. For example, this method could work at room temperature.”

A quantum Internet could offer applications that are impossible to implement in the conventional Internet, such as impenetrable security and quantum teleportation.

“An all-optical network is a promising form of infrastructure for fast and energy-efficient communication that is required for a future quantum internet,” says Lo. “Our work helps pave the way toward this future.”

Learn more: Toward a future quantum Internet

 

 

The Latest on: Quantum internet
  • Current encryption algorithms still strong, NIST official says
    on December 6, 2019 at 12:53 pm

    NIST is currently working on a number of initiatives to develop more-modern cryptographic algorithms – ones that resist codebreaking efforts from quantum computers as well as new standards for smaller ...

  • AWS Crowdsources Its Quantum Computing Future
    on December 6, 2019 at 6:56 am

    For the most part, quantum computing hype is far ahead of reality. Quantum computers may be available to experiment with over the internet and through cloud services like AWS Braket. But they are ...

  • This Week in Tech: What on Earth Is a Quantum Computer?
    on December 6, 2019 at 6:00 am

    Quantum computers manipulate qubits with exquisite control ... Instagram now requires birth dates from all users as it tries to protect young people from the dark side of the internet. So said Reuters ...

  • Quantum Trends And The Internet of Things
    on December 5, 2019 at 4:53 pm

    There is an additional “entanglement” relating to quantum, and that is its intersection with the Internet of Things (IoT). Loosely defined, the Internet of Things (IoT) refers to the general idea of ...

  • NIST official says post-quantum environment still years away
    on December 5, 2019 at 12:23 pm

    Despite recent industry claims of quantum supremacy ... computers as well as new standards for smaller "lightweight" and internet-of-things devices that have become more prevalent over the ...

  • China steals U.S.-funded quantum research
    on December 4, 2019 at 1:57 pm

    Quantum technology and computing provide extremely secure ... represents our nation’s future is being stolen right before our eyes.” China’s Sina.com internet site for the first time revealed Tehran’s ...

  • Amazon offers quantum computing on its AWS servers
    on December 3, 2019 at 4:10 pm

    ... which up until now has been pretty quiet on the quantum front -- has plans to offer a quantum computing service to companies through the internet, thereby eliminating some of the costs and other ...

  • Amazon is now offering quantum computing as a service
    on December 2, 2019 at 3:20 pm

    its attempt to turn the nascent field of quantum computing into a service you can access over the internet, a month after Microsoft did something similar. “Amazon Braket is a fully managed AWS service ...

  • Qubits on the Move: QuTech and the Quantum Internet
    on December 2, 2019 at 1:01 pm

    One such idea was the focus of a plenary at the conference: the creation of a quantum internet. Ronald Hanson, Scientific Director at the QuTech research institute and a professor at the Delft ...

  • Amazon Joins Tech’s Great Quantum Computing Race
    on December 2, 2019 at 4:30 am

    Amazon is not the first to launch a quantum cloud service either. IBM has offered access to its own quantum hardware over the internet since 2016 and Google says it will soon do the same. Microsoft, ...

via  Bing News