Xanadu has achieved a four-fold reduction in compute requirements for quantum applications through combined algorithmic innovations, compared to legacy industry approaches, the company says. The company’s latest breakthrough builds upon its May 2026 Quantum Read-Only Memory (QROM) work, halving the computational cost of this data loading component for a second time.
This advance significantly reduces the number of Toffoli gates, among the most computationally expensive operations for quantum computers, and enables more impactful commercial use cases. The Xanadu team believes that by making better use of the limited number of available qubits, dense encoding will address one of the primary bottlenecks facing near-term hardware.
Sequential Bit Packets & QROM Optimization
Xanadu achieved a two-fold acceleration in quantum read-only memory (QROM) efficiency through dense encoding, building on previous work with sequential bit packets. This latest advancement stores two bits of classical information within each dirty qubit, using both its binary value and phase to maximize data density, according to Xanadu. The result achieves this by breaking up a larger lookup table into a sequence of smaller ones to make better use of dirty qubits by sharing table passes across the smaller tables.
Data loading, the process of transferring classical information to quantum hardware, represents a dominant source of computationally expensive gates in most practical quantum applications, making this improvement significant. Xanadu’s team focused on optimizing this critical component, recognizing that reducing QROM cost directly translates to more efficient algorithms.
The team’s earlier work, published in May 2026, already halved the resource cost of a key building block for quantum applications, and this new technique further reduces that cost, establishing a new benchmark for QROM efficiency. This halving of the cost of QROM for the second time in under a year, Xanadu believes, brings universal scalable quantum computing one step closer for the industry.
Dense Encoding Further Reduces QROM Computational Cost
Dense encoding further accelerates quantum read-only memory (QROM) efficiency, delivering a two-fold increase in speed when used alongside Xanadu’s sequential bit packets construction. The team’s research, recently published on the arXiv, directly addresses a long-standing bottleneck in data loading for quantum computers.
Historically, QROM performance had plateaued for nearly seven years, presenting a significant cost and hardware challenge, but Xanadu’s advancements offer immediate benefits for near-term utility-scale quantum computers. This latest breakthrough not only improves algorithmic efficiency but also positions Xanadu to significantly lower the cost of quantum applications for the industry.
Source: https://www.xanadu.ai/blog/halving-the-cost-of-qrom-again
