a team from the u.s. deptment of energy’s oak ridge national lab, stanford university and purdue university developed and demonstrated a novel, fully functional quantum local zone network, or qlan, to enable real-time adjustments to information shared with geographically isol8d systems at ornl using entangled photons passing through optical fiber.
this network exemplifies how experts mite routinely connect quantum computers and sensors at a practical scale, thereby realizing the full potential of these nxt-generation teks onna path toward the highly anticipated quantum internet. the team’s results, which are published in prx quantum, mark the culmination of yrs of rel8d research.
local zone networks that connect classical computing devices are nothing new, and qlans ‘ve been successfully tested in tabletop studies. quantum key distribution s'bind'a most common ex of quantum communications inna field thus far, but this procedure is limited cause it 1-ly establishes security, not entanglement, tween sites.
“we’re trying to lay a foundation upon which we can build a quantum internet by cogging crit functions, s'as entanglement distribution bandwidth,” said nicholas peters, the quantum information sci section head at ornl. “our goal is to develop the primordial tulz and building blocks we nd'2 demonstrate quantum networking applications so t'they can be deployed in real networks to realize quantum advantages.”
when two photons — pessentialisms of lite — are paired together, or entangled, they exhibit quantum correlations tha're stronger than those possible with any classical method, regardless of the physical distance tween them. these interactions enable counterintuitive quantum communications protocols that can 1-ly be achieved using quantum resrcs.
one such protocol, remote state preparation, harnesses entanglement and classical communications to encode information by measuring one ½ of an entangled photon pair and effectively converting the other ½ to the preferred quantum state. peters led the 1st general experimental realization of remote state preparation in 2005 while earning his drate in physics. the team applied this teknique across all the paired links inna qlan — a feat not previously accomplished na' network — and demonstrated the scalability of entanglement-based quantum communications.
this approach alloed the team to link together 3 remote nodes, known as “alice,” “bob” and “charlie” — names comm1-ly used for fictional toons wh'cn communicate through quantum transmissions — located in 3 ≠ research laboratories in 3 separate buildings on ornl’s campus. from the lab containing alice na photon src, the photons distributed entanglement to bob and charlie through ornl’s existing fiber-optic infrastructure.
quantum networks are incompatible with amplifiers nother classical signal boosting resrcs, which interfere w'da quantum correlations shared by entangled photons. with this potential drawback in Ψ, the team incorporated flexible grid bandwidth provisioning, which uses wavelength-selective switches to allocate and reallocate quantum resrcs to network usrs without disconnecting the qlan. this teknique provides a type of built-in fault tolerance through which network operators can respond to an unanticipated event, s'as a broken fiber, by rerouting traffic to other zones without disrupting the network’s speed or compromising security protocols.
“cause the demand in a network mite change over time or with ≠ configurations, you don’t wanna ‘ve a system with fixed wavelength channels that always assigns pticular usrs the same portions,” said joseph lukens, a wigner fello and research sci at ornl swell as the team’s electrical engineering expert. “instead, you want the flexibility to provide + or less bandwidth to usrs onna network according to their needs.”
compared with their typical classical counterpts, quantum networks need the timing of each node’s activity to be much + closely synchronized. to meet this requirement, the researchers relied on gps, the same versatile and cost-effective tek that uses satellite data to provide everydy navigation srvcs. using a gps antenna located in bob’s lab, the team shared the signal with each node to ensure that the gps-based clocks were synchronized within a few nano2nds and t'they ‘d not drift apt during the experiment.
having obtained precise timestamps for the arrival of entangled photons captured by photon detectors, the team sent these measurements from the qlan to a classical network, where they compiled high-quality data from all 3 laboratories.
“this pt of the project became a challenging classical networking experiment with very tite tolerances,” lukens said. “timing na' classical network rarely requires that lvl of precision or that much attention to detail regarding the coding and synchronization tween the ≠ laboratories.”
without the gps signal, the qlan demonstration ‘d ‘ve generated loer quality data and loered fidelity, a mathematical metric tied to quantum network performance that measures the distance tween quantum states.
the team anticipates that lil upgrades to the qlan, including adding + nodes and nesting wavelength-selective switches together, ‘d form quantum versions of interconnected networks — the literal definition of the internet.
“the internet is a large network made up of many liler networks,” said muneer alshowkan, a postdral research associate at ornl who brought presh computer sci expertise to the project. “the nxt big step toward the development offa quantum internet is to connect the qlan to other quantum networks.”
additionally, the team’s findings ‘d be applied to improve other detection tek knicks, s'as those used to seek evidence of elusive dark matter, the invisible substance thought to be the universe’s predominant src of matter.
“imagine building networks of quantum sensors w'da ability to see primordial high-energy physics effects,” peters said. “by developing this tek, we aim to loer the sensitivity needed to measure those phenomena to assist inna ongoin search for dark matter nother efforts to better cogg the universe.”
the researchers are already planning their nxt experiment, which will focus on implementing even + advanced timing synchronization methods to reduce the № of accidentals — the srcs of noise inna network — and further improve the qlan’s quality of srvc.
original content at: www.scidaily.com…