The quantum computing company Alice & Bob has announced a new method for stabilizing its cat qubits. Cat qubits are a type of multi-qubit superposition that mimics the macroscopic superposition idea of Schrödinger's cat. The company says this method can achieve up to 160 times better bit-flip error protection. The approach involves "squeezing" cat qubits or compressing their quantum states to optimize error suppression, and it is highlighted in a recent paper preprint.
Cat qubits, already under development by multiple teams, have gained wider attention recently through Amazon Web Services' Ocelot chip, which also uses cat qubits for error correction. Alice & Bob's design aims to make these cat qubits more resistant to bit-flips without increasing phase-flip errors.
"Standard cats, those that are not squeezed, offer significant advantages, but their bit-flip improvements come at a cost on the phase-flip error channel," said Raphael Lescanne, CTO and co-founder of Alice & Bob. "By squeezing our cats, we can enhance bit-flip protection without compromising phase-flip performance, making phase-flip correction more manageable in the long run."
Error correction is seen as a major hurdle in quantum computing, where the fragility of qubits often leads to calculation errors. Cat qubits are designed to reduce bit-flips, making error correction less resource-intensive. However, increasing the qubit (by increasing photons) can lead to more phase-flips, creating a tradeoff the team is attempting to address with squeezing.
"The goal with squeezing is to make every photon count," said Anil Murani, senior researcher and Fellow Expert at Alice & Bob. "Our latest innovation makes our cat qubits more well-rounded and squeezes even greater protection out of them, which will ease the requirements on error correction."
According to Alice & Bob, experiments show that cat qubits without squeezing can achieve a bit-flip lifetime of 138 milliseconds, surpassing many superconducting platforms. By applying squeezing and adjusting the number of photons to 4.1, the bit-flip lifetime reportedly reached 22 seconds, with no significant increase in phase-flip errors.
"By enhancing qubit performance without modifying circuit design, this simple yet effective technique positions our platform to deliver high-fidelity logical qubits at an even smaller fraction of the cost of alternative approaches,"
Alice & Bob is one of several organizations working with cat qubits, each seeking to address the balance between error mitigation and scalability. The company aims to move toward universal fault-tolerant quantum computing, where both bit-flips and phase-flips can be managed efficiently, potentially opening the door to practical applications in chemistry, materials science, and beyond.