Month: August 2024

Under the streets of New York City, they’re testing a “quantum network,” reports Phys.org — where engineers from a Brooklyn company named Qunnect Inc are taking steps to “overcome the fragility of entangled states in a fiber cable and ensure the efficiency of signal delivery.”

For their prototype network, the Qunnect researchers used a leased 34-kilometer-long fiber circuit they called the GothamQ loop. Using polarization-entangled photons, they operated the loop for 15 continuous days, achieving an uptime of 99.84% and a compensation fidelity of 99% for entangled photon pairs transmitted at a rate of about 20,000 per second. At a half-million entangled photon pairs per second, the fidelity was still nearly 90%…
They sent 1,324 nm polarization-entangled photon pairs in quantum superpositions through the fiber, one state with both polarizations horizontal and the other with both vertical — a two-qubit configuration more generally known as a Bell state. In such a superposition, the quantum mechanical photon pairs are in both states at the same time.

“While others have transmitted entangled photons before, there has been too much noise and polarization drift in the fiber environment for entanglement to survive,” the article points out, “particularly in a long-term stable network.” So the Qunnect team built “automated polarization compensation” devices to correct the polarization of the entangled pairs:

In their design, an infrared photon [with a wavelength of 1,324 nanometers] is entangled with a near-infrared photon of 795 nanometers. The latter photon is compatible in wavelength and bandwidth with the rubidium atomic systems, such as are used in quantum memories and quantum processors. It was found that polarization drift was both wavelength- and time-dependent, requiring Qunnect to design and build equipment for active compensation at the same wavelengths…
Qunnect’s GothamQ loop demonstration was especially noteworthy for its duration, the hands-off nature of the operation time, and its uptime percentage. It showed, they wrote, “progress toward a fully automated practical entanglement network” that would be required for a quantum internet.

And Qunnect’s co-founder/chief science officer says “since we finished this work, we have already made all the parts rack-mounted, so they can be used everywhere…”

Their network design and results are published in PRX Quantum.

Read more of this story at Slashdot.

Under the streets of New York City, they’re testing a “quantum network,” reports Phys.org — where engineers from a Brooklyn company named Qunnect Inc are taking steps to “overcome the fragility of entangled states in a fiber cable and ensure the efficiency of signal delivery.”

For their prototype network, the Qunnect researchers used a leased 34-kilometer-long fiber circuit they called the GothamQ loop. Using polarization-entangled photons, they operated the loop for 15 continuous days, achieving an uptime of 99.84% and a compensation fidelity of 99% for entangled photon pairs transmitted at a rate of about 20,000 per second. At a half-million entangled photon pairs per second, the fidelity was still nearly 90%…
They sent 1,324 nm polarization-entangled photon pairs in quantum superpositions through the fiber, one state with both polarizations horizontal and the other with both vertical — a two-qubit configuration more generally known as a Bell state. In such a superposition, the quantum mechanical photon pairs are in both states at the same time.

“While others have transmitted entangled photons before, there has been too much noise and polarization drift in the fiber environment for entanglement to survive,” the article points out, “particularly in a long-term stable network.” So the Qunnect team built “automated polarization compensation” devices to correct the polarization of the entangled pairs:

In their design, an infrared photon [with a wavelength of 1,324 nanometers] is entangled with a near-infrared photon of 795 nanometers. The latter photon is compatible in wavelength and bandwidth with the rubidium atomic systems, such as are used in quantum memories and quantum processors. It was found that polarization drift was both wavelength- and time-dependent, requiring Qunnect to design and build equipment for active compensation at the same wavelengths…
Qunnect’s GothamQ loop demonstration was especially noteworthy for its duration, the hands-off nature of the operation time, and its uptime percentage. It showed, they wrote, “progress toward a fully automated practical entanglement network” that would be required for a quantum internet.

And Qunnect’s co-founder/chief science officer says “since we finished this work, we have already made all the parts rack-mounted, so they can be used everywhere…”

Their network design and results are published in PRX Quantum.

Read more of this story at Slashdot.

Read More 

Monday brought spectacular footage of an explosion at a UK rocket test site after an engine test went awry. The plan had been to test-fire all of a rocket stage’s nine engines at the same time — they’ve successfully ignited the mores more than a hundred times — but this time one of the first eight had an “unusual” anomaly — “most likely a fire in the oxygen pump,” according to a video posted by space company RFA on X.com.

The trouble “spread onto neighboring engines,” eventually leading to a billowing jet of fire from the side of the vehicle. (“The engine-propellant manifold system was damaged to such a great extent that kerosene kept fueling the fire.”)

Slashdot reader AleRunner writes:

A rocket company has vowed to return to regular operations “as soon as possible” after an explosion during a test at the UK’s new spaceport in Shetland. The explosion happened after “an “anomaly” had led to “the loss of the stage” — but there were no injuries according to a Guardian report. The test was carried out by German company Rocket Factory Augsburg which hopes to make the first UK vertical rocket launch into orbit… “We develop iteratively with an emphasis on real testing.”This is part of our philosophy and we were aware of the higher risks attached to this approach. Our goal is to return to regular operations as soon as possible.”
“In true RFA fashion, we’re being as transparent as possible,” the company posted Friday on X.com, “and sharing our own raw footage of the incident.” The day of the explosion they’d posted that “The launch pad has been saved and is secured,” and Friday posted that six-minute video explaining what happened. (It emphasizes there’s an improved version of this stage that’s already been built.)

The Guardian added that the explosion comes three months after RFA’s successful 8-second test firing of its rocket engines — the spaceport’s first rocket test.

Read more of this story at Slashdot.

Monday brought spectacular footage of an explosion at a UK rocket test site after an engine test went awry. The plan had been to test-fire all of a rocket stage’s nine engines at the same time — they’ve successfully ignited the mores more than a hundred times — but this time one of the first eight had an “unusual” anomaly — “most likely a fire in the oxygen pump,” according to a video posted by space company RFA on X.com.

The trouble “spread onto neighboring engines,” eventually leading to a billowing jet of fire from the side of the vehicle. (“The engine-propellant manifold system was damaged to such a great extent that kerosene kept fueling the fire.”)

Slashdot reader AleRunner writes:

A rocket company has vowed to return to regular operations “as soon as possible” after an explosion during a test at the UK’s new spaceport in Shetland. The explosion happened after “an “anomaly” had led to “the loss of the stage” — but there were no injuries according to a Guardian report. The test was carried out by German company Rocket Factory Augsburg which hopes to make the first UK vertical rocket launch into orbit… “We develop iteratively with an emphasis on real testing.”This is part of our philosophy and we were aware of the higher risks attached to this approach. Our goal is to return to regular operations as soon as possible.”
“In true RFA fashion, we’re being as transparent as possible,” the company posted Friday on X.com, “and sharing our own raw footage of the incident.” The day of the explosion they’d posted that “The launch pad has been saved and is secured,” and Friday posted that six-minute video explaining what happened. (It emphasizes there’s an improved version of this stage that’s already been built.)

The Guardian added that the explosion comes three months after RFA’s successful 8-second test firing of its rocket engines — the spaceport’s first rocket test.

Read more of this story at Slashdot.

Read More