Synthetic Lattice for a Single Photon ⚡ экспресс
Synthetic frequency dimensions are often used to simulate lattice models and control photonic dynamics, but transferring this to the single-photon quantum regime has remained a challenging task. In this work, initialization and detection of quantum states of single photons in such a lattice was realized for the first time using a superconducting qubit integrated with a 16-meter aluminum coaxial cable. The lattice couplings and artificial gauge fields are created by a tunable SQUID-based modulator. Quantum random walks, Bloch oscillations, and non-adiabatic unidirectional frequency conversion under fast temporal modulation of the lattice Hamiltonian were demonstrated; the band structure was measured. The coupling topology can easily be reconfigured into multidimensional lattices using a few control tones. Thus, superconducting quantum circuits provide a universal platform for programmable Hamiltonians and scalable synthetic lattices with flexible control at the single-photon level.
A photon is like a car in a multi-story parking lot, where each floor is its frequency (color). Usually it gets stuck on one level, but scientists added an elevator — a programmable modulator that moves the photon between floors on command. This elevator creates links between frequencies, turning them into an artificial lattice, reminiscent of the method of studying light by its frequencies — spectroscopy.
By changing the elevator’s mode, you can get the photon to wander randomly across floors, rhythmically swing up and down, or strictly move only upward with no return. In the experiment, a single photon was born in a superconducting qubit — an artificial atom developed thanks to the discoveries of Bardeen — and raced along a 16-meter cable at nearly the speed of light. The statistics of its jumps obeyed laws studied by Roy Glauber.
🎯 The 16-meter cable length isn’t random: it set the spacing between frequency floors at about 10 MHz so they could be resolved and controlled individually.