Beneath the City: A 21-Mile Quantum Network in the Heart of New York
The bustling streets of New York City hold a secret beneath their surface: a 21-mile-long quantum network operating on the city’s existing telecommunications infrastructure. For 15 days in December, Qunnect, a quantum hardware company, ran a groundbreaking experiment on its GothamQ testbed, transmitting entangled photons through optical fibers, pushing the boundaries of quantum communication. While the concept of a "quantum internet" remains a futuristic dream, this experiment represents a substantial step towards a reality where quantum information can flow freely through existing infrastructure.
The Quantum Edge:
Qunnect’s experiment harnessed the power of entanglement, a key concept in quantum mechanics. Entanglement links two particles, in this case, photons, in a special way. Measuring the state of one entangled photon instantaneously reveals the state of its counterpart, even if they are separated by vast distances. This unique property paves the way for secure communication and powerful quantum computing.
In the heart of GothamQ, pairs of entangled photons are generated using a vapor cell of rubidium-87. These entangled photons serve as qubits – the building blocks of quantum computers. Unlike classical bits, which can only be 0 or 1, qubits can exist in a superposition of states, allowing for far greater computational power.
The experiment achieved a remarkable feat, transmitting half a million entangled photon pairs per second through the network. This shattered previous records set by similar experiments, which only reached rates of 10,000 to 20,000 pairs per second. "It’s always hard to explain what a next-generation infrastructure is going to do for you," says Mehdi Namazi, Qunnect’s Chief Science Officer. "It’s like defining what would’ve been the application of the internet.”
The Advantage of Light:
Unlike fragile quantum computers requiring ultra-cold temperatures, photons can carry quantum information at ambient conditions. This allows for the groundbreaking utilization of existing, large-scale infrastructure, eliminating the need for costly and intricate laboratory setups.
A critical aspect of the experiment was the use of time multiplexing. The GothamQ network paused operations for milliseconds at a time, sending pulses of classical light through the system to gauge stability and detect any potential disruptions. This ingenious technique allowed for reliable operation with a staggering 99.84% uptime over the 15-day experiment. “Our work paves the way for practical deployment of 24/7 entanglement-based networks with rates and fidelity adequate for many current and future use-cases," the research team highlighted in their paper.
A Glimpse of the Future:
The immediate implications of this experiment lie in the realm of cybersecurity. Entangled photons can be used to generate unbreakable encryption keys. "If you can use these to send your 0s and 1s, or use them as a way to create a key for your encryption, it’s much, much harder to hack them," explains Namazi. "If something happened to one of your photons, the other one immediately knows. And there’s nothing a hacker can do about that because there is no way to replicate this kind of connection.”
While the transmission rate of the experiment, though impressive, is far from surpassing the current 5G standard, it marks a significant leap forward towards practical applications of quantum communication. The experiment demonstrates the feasibility of distributing entanglement reliably and securely over long distances, opening up a world of possibilities for quantum cryptography, quantum sensing, and ultimately, the quantum internet.
The Quantum Internet: A Vision of the Future:
The quantum internet is a vision of a future where data is transmitted using qubits instead of classical bits. This could revolutionize communication, allowing for:
- Unbreakable Encryption: Quantum key distribution, using entangled photons, would make communication impervious to hacking.
- Enhanced Computing Power: A quantum internet would enable powerful distributed quantum computation, solving complex problems beyond the reach of even the most powerful classical computers.
- Precise Sensing: Quantum networks could be used to create highly sensitive sensors for applications ranging from medical imaging to environmental monitoring.
While the quantum internet remains a long-term goal, the GothamQ experiment provides a tangible demonstration of the progress being made towards this future. As Dr. Namazi emphasizes, "Everything we’ve been trying to develop is around this idea of ‘is it practical?’ Can it practically distribute entanglement in a way that is so robust, stable, and high-quality that you can always be sure it’s useful in applications?"
A City in the Quantum Age:
The GothamQ experiment is a testament to the transformative power of quantum technology. It showcases the potential of quantum networks to revolutionize communication and computing, while demonstrating the practicality of utilizing existing infrastructure for this cutting-edge technology. As we navigate the exciting possibilities of the quantum age, the city that never sleeps may become the proving ground for the quantum internet, a network poised to reshape the world as we know it.
