10.8 Racetrack Memory
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stable smectic liquid-crystalline structure of skyrmions has also recently been
observed.
It is believed that racetrack memory should, 1 day, work in a similar way
to punched tape technology back when computers were still in their infancy.
During those days, ‘hole’ was used to represent 1 and ‘no hole’ was used to
represent 0. In future, a ‘skyrmion’ would represent 1 and ‘no skyrmion’ would
represent 0. Voltage should permit the skyrmions to travel over to a read head,
one after another.
10.9 Quantum Computing
Computer is the most essential device in our modern-day life. With the advent
of research in semiconductor technology and information processing, as the time
elapsed, the size of our computer became smaller and smaller and its computational
power increased manifold. But our binary computer is not fast enough to calculate
more difficult problems where higher computing power is needed. For example,
finding an item from an unsorted big database or factoring big integers needs high
computational power, sometimes so high that practically limits our binary computers
to solve the problems. So, we need some special type of computer which should
be very fast compared to classical binary computer. To meet the need, a new type
of computers based on the principle of quantum mechanics are being studied and
developed globally. These computers are called quantum computer.
Quantum computer is acting on the principle of quantum mechanics. Our current
binary computers manipulate and store information as binary bits (0 and 1). In the
physical level, binary bits correspond to binary states (i.e., high or low voltage) of
logic devices. On the other hand, quantum computers process information as quantum
bits or Qubits. Unlike a binary bit, which corresponds to a binary electronic state of
logic device and has only value either 0 or 1, a quantum bit is superposition of binary
states, which can hold both the values 0 and 1 at the same time. For example, electrons
with up or down spin orientations represent the binary values 0 or 1. Superposition
of electronic states leads us to the realization that the electron is spinning a little bit
up and little bit down at the same time, i.e., the electron could represent both the bit
values 0 and 1, simultaneously. This is quantum bit or Qubit.
10.9.1 Bloch Sphere Representation
We may use Bloch sphere to realize the possible quantum states associated with a
single Qubit, as shown in Fig. 10.24. In this sphere, the position of classical bits
261
stable smectic liquid-crystalline structure of skyrmions has also recently been
observed.
It is believed that racetrack memory should, 1 day, work in a similar way
to punched tape technology back when computers were still in their infancy.
During those days, ‘hole’ was used to represent 1 and ‘no hole’ was used to
represent 0. In future, a ‘skyrmion’ would represent 1 and ‘no skyrmion’ would
represent 0. Voltage should permit the skyrmions to travel over to a read head,
one after another.
10.9 Quantum Computing
Computer is the most essential device in our modern-day life. With the advent
of research in semiconductor technology and information processing, as the time
elapsed, the size of our computer became smaller and smaller and its computational
power increased manifold. But our binary computer is not fast enough to calculate
more difficult problems where higher computing power is needed. For example,
finding an item from an unsorted big database or factoring big integers needs high
computational power, sometimes so high that practically limits our binary computers
to solve the problems. So, we need some special type of computer which should
be very fast compared to classical binary computer. To meet the need, a new type
of computers based on the principle of quantum mechanics are being studied and
developed globally. These computers are called quantum computer.
Quantum computer is acting on the principle of quantum mechanics. Our current
binary computers manipulate and store information as binary bits (0 and 1). In the
physical level, binary bits correspond to binary states (i.e., high or low voltage) of
logic devices. On the other hand, quantum computers process information as quantum
bits or Qubits. Unlike a binary bit, which corresponds to a binary electronic state of
logic device and has only value either 0 or 1, a quantum bit is superposition of binary
states, which can hold both the values 0 and 1 at the same time. For example, electrons
with up or down spin orientations represent the binary values 0 or 1. Superposition
of electronic states leads us to the realization that the electron is spinning a little bit
up and little bit down at the same time, i.e., the electron could represent both the bit
values 0 and 1, simultaneously. This is quantum bit or Qubit.
10.9.1 Bloch Sphere Representation
We may use Bloch sphere to realize the possible quantum states associated with a
single Qubit, as shown in Fig. 10.24. In this sphere, the position of classical bits