IBM Comes Clean in Quantum Computing! Introduces Error Mitigation Technique

IBM's technique relies on comprehending the reason for noise rather than eliminating it completely

IBM has good news for quantum computing enthusiasts. It has developed error mitigation strategies to make fault-tolerant quantum computers. While this news may not be of any significance or even comprehensible to the common man, IT experts and business leaders know what it means to the industry. The IBM team in its blog writes, "Recent advances in techniques we refer to broadly as quantum error mitigation allow us to lay out a smoother path towards this goal. Along this path, advances in qubit coherence, gate fidelities, and speed immediately translate to measurable advantage in computation, akin to the steady progress historically observed with classical computers." The quantum error mitigation strategies would definitely bridge the gaps in the transition towards quantum computing, a narrative that was missing earlier.

Qubits do get noisy

Quantum computing, in recent times, has grabbed a lot of attention because of its fast and complex computing capabilities. A normal person may not understand what the buzz is all about but industry experts do understand the shift in computing it can bring. Quantum computers employ qubits to store and process information. Qubits are quantum states which can exist in different states simultaneously, a character that makes simultaneous calculations possible. But unlike their classical counterparts, the digital bits which take only either 0 or 1, are highly fragile, susceptible to losing information easily through interactions with their environment. One of the major causes of fragility is noise which greatly hinders a quantum computer's capability. Even a minor fluctuation in temperature, noise, or interactions with its surroundings can disturb its functioning. This is one of the main reasons why quantum computing seems like a distant dream, though it holds the potential to surpass supercomputing.  

Quantum errors are complex so is the correction strategy

Unlike classical bits which take only two states, qubits can have several in-between states due to superposition which can account for errors too. Quantum error correction starts with encoding information using redundant qubits, providing quantum information to them. As the quantum information disrupts the normal quantum states, the induced noise is decoded, thereby allowing us to understand how the error affects the encoded information. Parity measurements come into play, as the computational qubits are tagged with helper quantum bits to measure the indirect signs of error.

Taking one step at a time

 IBM's strategy doesn't aim to eliminate qubits altogether but extract value from them and make quantum computing move away from the dreaded NISQ (Noisy Intermediate-Scale Quantum) stage. To get error-free results IBM has tried inverting noisy quantum circuits, all while retaining noisy qubits. This technique throws light on the noise causing the error though at the cost of losing runtime. IBM was working on error mitigation strategies for many years though in incremental steps. Last year it released the 127-qubit Eagle processor, taking the stimulability factor beyond the limits of a classical computer. The most common error mitigation methods IBM was working on include PEC or Probabilistic Error Correction. Through PEC and the other method ZEC, Zero Noise Extrapolation, which in themselves are complex applications of quantum mechanics – find a way to eliminate or reduce the noise levels. IBM's error mitigation approach "is the continuous path that will take us from today's quantum hardware to tomorrow's fault-tolerant quantum computers. This path will let us run larger circuits needed for quantum advantage, one hardware improvement at a time.", say its bloggers. Clearly, IBM's PEC strategy is a departure from the earlier error mitigation approaches not just for IBM but for the entire quantum field. Instead of working on full error mitigation, its approach is akin to taking one step at a time and reaching a milestone, while still having a long path to traverse.